JPH0456674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrostatic coating device that applies a voltage between an object to be coated and a coating material to perform electrical transmission. This invention relates to an electrostatic coating device that can be used for both atomization and atomization purposes.

(Prior art) An electrostatic coating device is equipped with a cup-shaped head that is driven to rotate, and for example, paint supplied to the center of the rotation is discharged from the tip by centrifugal force.
Until this discharge, the paint is charged so as to have a potential difference with respect to the object to be coated.
There are two types of devices equipped with such cup-shaped heads: those for rotary atomization and those for air atomization, and their use was determined depending on the type of paint.

In other words, in the case of rotary atomizers, the cup-shaped head is rotated at a high speed of, for example, 8,000 to 12,000 revolutions per minute, and the paint is sprayed by the action of centrifugal force.
While atomizing the paint to a fine size of about 40 to 70 microns (for atomization), shaping air is blown out from around the rotary atomizer to shape the release pattern of the ejected paint. In addition, for air atomization, the cup-shaped head has a speed of, for example, 3000 to 3000 per minute.
The paint is rotated at a low speed of 4,000 rpm to thin the paint to about 300 to 400 microns by the action of centrifugal force, and then the paint is thinned from the cup-shaped head by atomizing air jetted from around the cup-shaped head. 40 paint released
The particles are atomized to ~70μ (for atomization). For example, when a solid paint is used, the coating is performed by rotary atomization, and when a metallic paint is used, the painting is performed by air atomization.
In this way, the reason why rotary atomization and air atomization are used depending on the type of paint is because, for example, when a metallic paint is rotary atomized, the metals in the paint coagulate on the painted surface. This is because the entire painted surface becomes dark, so air atomization has to be used.

In this way, using air atomization and rotary atomization depending on the type of paint requires separate painting equipment for air atomization and rotary atomization, which increases installation costs. Of course, each time the type of paint is changed, the arrangement must be changed between air atomization and rotary atomization, making the so-called setup change extremely troublesome. In particular, recently, objects to be coated with different types of paint often flow together on one line, and when the objects to be painted mixed and flowing are extremely large, such as automobile bodies, Since it is necessary to use a plurality of rotary atomization devices or a plurality of air atomization devices at the same time, the above-mentioned problems become noticeable.

(Object of the invention) The present invention has been made in consideration of the above circumstances, and has a cup-shaped head that can be used for both rotational atomization and air atomization. An object of the present invention is to provide an electrostatic coating device that can freely switch between atomization and air atomization.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention basically rotates the cup-shaped head at high speed and low speed depending on whether it is for rotary atomization or air atomization. On the other hand, the air jet, that is, the shaping jet necessary for high-speed atomization in which the cup-shaped head is rotated at high speed, and the atomizing air jet necessary for air atomization in which the cup-shaped head is rotated at low speed. is performed in accordance with this high-speed rotation or low-speed rotation.

Specifically, in a device that performs painting while applying a voltage between the object to be coated and the paint, it is equipped with a cup-shaped head that is rotationally driven by a rotary motor, and the paint supplied to the cup-shaped head is output from a distance. a paint ejector that discharges paint from the tip of the cup-shaped head; a rotary motor control device that switches the rotation of the rotary motor between high-speed rotation for rotary atomization and low-speed rotation for air atomization; A shaping air outlet is provided around the head, and at least when the rotary motor is rotated at high speed, air is jetted from the shaping air outlet, and the paint is discharged from the tip of the cup-shaped head. a pattern-shaping air blowout device for controlling a discharge pattern of the air, and an atomizing air blowout provided around the cup-shaped head, the air blowing device controlling the air blowing from the atomizing air blowout when rotating the rotary motor at a low speed. Blow out air,
An atomizing air blowing device for atomizing the paint ejected from the tip of the cup-shaped head.

(Example) Examples of the present invention will be described below with reference to the attached drawings.

In FIG. 1, reference numeral 1 denotes a cylindrical main body, and a cylindrical rotating shaft 3 is rotatably disposed and held in a hollow portion 2 of the main body. This rotary shaft 3 is driven by an air motor 4 as a rotary motor attached to the rear end of the main body 1, and a rotary shaft 3 is installed at the front end of the rotary shaft 3 as shown in FIG. A cup-shaped head 5, so-called a bell, is concentrically threaded and integrated.

The cup-shaped head 5 is located in a storage recess 6 formed on the front end side of the main body 1 and having a substantially semicircular cross section, and its front surface gradually increases as it goes radially outward from the center of rotation. It is said to be a curved surface that looks forward. As shown in detail in FIG. 2, this cup-shaped head 5 has a tapered communication opening 7 formed at its center of rotation, and the rotating shaft 3 and the inside thereof are fitted into this communication opening 7. Nozzle 10
The paint is supplied through the gap 8 between the nozzle 10 or the passage formed within the nozzle 10. In addition, the cup-shaped head 5 has a disc-shaped flow dividing plate 9 disposed on the front surface of the communication port 7, while
Inside the rotating shaft 3, there is a communication port 7 facing the communication port 7.
The above-mentioned nozzle 10 for opening and closing is disposed so as to be freely displaceable in the front-rear direction. The paint is supplied to the communication port 7 (the same applies to the supply of cleaning thinner when changing colors) through a pipe 11 connected to the connection 8a provided at the rear end of the air motor 4.
Opening and closing of the communication port 7 by the nozzle 10 is performed via an actuator (not shown) in response to air supply and discharge from a pipe 12 connected to a connection port 10a provided at the rear wheel portion of the air motor 4. It is now being carried out by

The front end of the main body 1 surrounds the tip of the cup-shaped head 5, and as shown in FIG. The air outlet 14 is
Each has a large number of openings spaced apart in the circumferential direction. Of the two air jet ports 13 and 14, the air jet port 13 shapes the paint discharge pattern during rotational atomization, so the jet direction is directed toward the front of the main body 1 (cup-shaped head 5). It is oriented so as to gradually expand outward in the radial direction (see the dashed-dotted line arrows in FIGS. 1 and 2).
In addition, the air jet port 14 atomizes the paint during air atomization, so the direction of the air jet port 14 is limited to the main body 1.
As it goes toward the front of the cup-shaped head 5, it is oriented so as to converge toward the center in the radial direction (see broken line arrows in FIGS. 1 and 2). Of course, both the air outlets 13 and 14 are connected to the air supply path 15 or 16.
are connected to dedicated air supply devices, which will be described later.

The air supply path 15 for the shaping air is
Connection part 15a provided at the rear end of the air motor 4
The air tank 18 is connected to an air tank 18 via a pipe 17 connected to the air tank 18, and an on-off valve 19 is connected in the middle of the pipe 17. The air supply path 16 for air atomization is connected to an air tank 21 via a pipe 20 connected to a connecting portion 16a provided at the rear end of the air motor 4, and an on-off valve is provided in the middle of this pipe 20. 22 are connected. Of course, of the two air tanks 18 and 21, the air tank 18 is filled with relatively low-pressure air for shaping (for example, 0.5 kg/min).
cm ² ) is stored in the air tank 21, and relatively high pressure air for air atomization (for example, 4 to 5 kg/cm 2 ) is stored in the air tank 21.
cm ² ) of air is stored.

The rotation speed of the air motor 4 is changed according to the supplied air pressure, and in order to change the rotation speed of the air motor 4, the connecting portion 4a is
A common pipe 23 is connected to. This common pipe 23 is branched into two in the middle, one branch pipe 23a is connected to an air tank 24, and the other branch pipe 23b is connected to an air tank 25.
An on-off valve 26 or 27 is connected to both branch pipes 23a and 23b. Of the two air tanks 24 and 25, the air tank 24 contains low-pressure air (for example, 0.5 Kg/cm ² ) to rotate the air motor 4 at a low speed (for example, 3000 revolutions per minute) suitable for air atomization. The air tank 25 also stores high-pressure air (for example, 4 kg/cm ² ) for making the air motor 4 rotate at a high speed (for example, 9,000 revolutions per minute) suitable for rotary atomization.

Next, the operation of the above configuration will be explained separately for the case where rotational atomization is performed and the case where air atomization is performed.

In the case of rotary atomization, for example, when painting with a solid paint, the on-off valves 22 and 26 are closed, while the on-off valves 19 and 27 are opened. As a result, the air motor 4, that is, the cup-shaped head 5 is rotated at high speed for rotational atomization, and the air for shaping is emitted from the air outlet 13 as shown in FIGS. 1 and 2.
It is ejected as shown by the dashed line arrow in the figure. Therefore, as shown by the solid line arrows in FIGS. 1 and 2, the paint supplied from the communication port 7 of the cup-shaped head 5 to the rotational center of the cup-shaped head 5 is transferred to the cup-shaped head by the action of centrifugal force. 5 flows outward in the radial direction, and is discharged from its tip toward the object to be coated. Of course, the paint discharged from the cup-shaped head 5 is sufficiently atomized (rotational atomization) because the cup-shaped head 5 is rotated at high speed.

In the case of air atomization, for example, when applying a metallic paint, the on-off valve 27 is closed, while the on-off valves 22 and 26 are opened. As a result, the air motor 4, that is, the cup-shaped head 5, is rotated at a low speed suitable for air atomization, and the air outlet 1 is rotated at a low speed suitable for air atomization.
4, atomizing air is blown out as shown by broken line arrows in FIGS. 1 and 2. Therefore, although the linear paint ejected from the cup-shaped head 5 is not sufficiently atomized compared to the case of rotary atomization,
After being sufficiently atomized by the action of the atomizing air, it heads toward the object to be coated. Note that the on-off valve 19 may be open or closed (in the case of air atomization, shaping air is not necessarily required, but this shaping air can also be used).

Here, the control of opening and closing of the on-off valves 19, 22, 26, and 27 associated with switching between rotary atomization and air atomization as described above is automatically performed by a control circuit (not shown). However, these on-off valves 1
9, 22, 26, and 27 should be explosion-proof, air-operated type when installed in or near the painting atmosphere, and electromagnetic type if they can be installed in a location that does not require special considerations for explosion-proofing. Can be done. Of course, the paint is charged while flowing through the cup-shaped head 5, and a predetermined potential difference is applied to the object to be coated.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
Since the cup-shaped head can be used for both rotational atomization and air atomization, it is possible to selectively switch between rotational atomization and air atomization in the same electrostatic coating device. Installation costs can be significantly reduced compared to conventional systems that require separate electrostatic coating devices for use and air atomization. In addition, when switching between rotary atomization and air atomization, there is no need to rearrange the electrostatic coating equipment itself, so the setup change between rotary atomization and air atomization can be done smoothly in a short time. can be done.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.
FIG. 2 is an enlarged sectional view of the main part of FIG. 1. Figure 3 is a half-simplified front view of the cup-shaped head and its surrounding parts, seen from the front side. 4: Air motor (rotating motor), 5: Cup-shaped head, 13: Shaping air outlet, 14: Atomizing air outlet, 18: Air tank (for shaping), 21: Air tank (for atomizing), 24: Air tank (for low speed rotation), 25: Air tank (for high speed rotation), 19, 22, 26, 27: Open/close valve.

Claims (1)

[Scope of Claims] 1. A device that performs painting while applying a voltage between the object to be coated and the paint, comprising a cup-shaped head that is rotationally driven by a rotary motor, and a paint that is supplied to the cup-shaped head. a paint ejector that discharges paint from the tip of the cup-shaped head by centrifugal force; a rotary motor control device that switches the rotation of the rotary motor between high-speed rotation for rotary atomization and low-speed rotation for air atomization; A shaping air outlet is provided around the cup-shaped head, and at least when the rotary motor is rotated at high speed, air is blown out from the shaping air outlet and released from the tip of the cup-shaped head. a pattern-shaping air jet device for controlling the release pattern of the paint; and an atomizing air jet port disposed around the cup-shaped head, and the atomizing air jet device controls the atomizing air jet when the rotary motor is rotated at a low speed. Air is blown out from the outlet,
An electrostatic coating device comprising: an atomizing air jet device that atomizes paint ejected from the tip of the cup-shaped head.