JP2776225B2 - Rotary atomization electrostatic coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating method capable of changing a coating color, and more particularly to a rotary atomizing static coating method for preventing troubles in a coating operation due to inflow of a detergent or paint. It relates to an electropainting method.

[0002]

2. Description of the Related Art In a vehicle paint line, the paint color of a vehicle body is different depending on the specification, so that the paint color is automatically switched. In the painting line of vehicles, painting work using a rotary atomizing electrostatic coating device is performed to increase the efficiency of coating paint on the vehicle body, and this rotary atomizing electrostatic coating device also has a color change function. Provided.

[0003] In a rotary atomizing electrostatic coating apparatus, paint is supplied to an atomizing head attached to the tip of a rotating shaft, and the paint is atomized by centrifugal force due to high-speed rotation of the atomizing head. The fine particles of the coating material are applied to the object to be coated by a suction force caused by an electrostatic field between the object and the object to be coated.

[0004] Usually, one fixed supply nozzle is disposed in the hollow portion of the rotary shaft. However, in order to save paint and cleaning agents when changing the color of the paint, a plurality of feed nozzles are provided in the hollow portion of the rotary shaft. A rotary atomizing electrostatic coating apparatus in which a paint nozzle and a cleaning agent passage are arranged has been previously proposed by the present applicant (Japanese Patent Application No. 5-102872).

In the rotary atomizing electrostatic coating apparatus disclosed in Japanese Patent Application No. 5-102872, a plurality of paint nozzles 3 are arranged in a hollow portion 2 of a rotating shaft 1 as shown in FIG.
Different paints can be supplied to the atomizing head 4 via each paint nozzle 3. Therefore, in the case of a specific paint color, the paint should be supplied from the paint nozzle 3 corresponding to the paint color, and it is not necessary to push out and discharge the paint in the paint nozzle 3 for color change. In addition, at the time of color change, only the atomizing head 4 needs to be cleaned with the cleaning agent from the cleaning agent passage 5 located on the outer periphery of the coating nozzle 3, and the cleaning of the coating nozzle 3 with the cleaning agent is unnecessary.

[0006]

However, the rotary atomizing electrostatic coating apparatus described above has the following problems. When the atomizing head 4 is washed, the cleaning agent (thinner) discharged from the cleaning agent passage 5 and the paint adhered to the tip of the paint nozzle 3 are filled with the hollow portion 2 of the rotary shaft 1 as shown by an arrow F.
And the rotating shaft 1 cannot rotate. When the paint discharged from the atomizing head 4 is directed upward, the paint discharged from the paint nozzle 3 flows back into the cleaning agent passage 5 under the influence of gravity, causing a problem of color mixing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary atomizing electrostatic coating method which can eliminate the trouble of the electrostatic coating operation due to the backflow of paint or cleaning agent.

[0008]

The rotary atomizing electrostatic coating method for achieving this object is constituted as follows. (1) A rotary atomizing electrostatic coating device in which a plurality of paint nozzles and a cleaning agent passage for cleaning an atomizing head attached to a tip of the rotary shaft are arranged in a hollow portion of the rotary shaft. The rotary atomizing electrostatic coating method used comprises a method of supplying compressed air to a hollow portion of a rotating shaft when the atomizing head is cleaned by the cleaning agent discharged from the cleaning agent passage. (2) A rotary atomizing electrostatic coating device in which a plurality of paint nozzles and a cleaning agent passage for cleaning an atomizing head attached to a tip of the rotary shaft are arranged in a hollow portion of the rotary shaft. The rotary atomizing electrostatic coating method used includes a method of always supplying compressed air to the cleaning agent passage except when the atomizing head is cleaned with a cleaning agent.

[0009]

In the rotary atomizing electrostatic coating method of the above (1), the compressed air is supplied to the hollow portion of the rotating shaft when the atomizing head is washed, so that the pressure in the hollow portion is reduced. The cleaning agent and the paint which are going to flow into the hollow portion can be pushed back. Therefore, the inflow of the cleaning agent and the paint into the hollow portion of the rotating shaft during the cleaning of the atomizing head is prevented, and the inability of the rotating shaft to rotate due to the inflow of the cleaning agent and the paint is eliminated.

In the above-mentioned rotary atomizing electrostatic coating method (2), compressed air is always supplied to the cleaning agent passage except when the atomizing head is cleaned with the cleaning agent. It is possible to push back the paint from the paint nozzle which is going to flow into the cleaning agent passage at the time of upward painting. Therefore, the paint is prevented from flowing into the cleaning agent passage at the time of the upward coating, and the color mixture caused by the paint flowing is eliminated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the rotary atomizing electrostatic coating method according to the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 4 show an embodiment of the present invention. First, the configuration of an apparatus for implementing the present invention will be described. In the figure, reference numeral 10 denotes a rotary atomizing electrostatic coating apparatus, and the rotary atomizing electrostatic coating apparatus 10 has a resin case 11 extending in the axial direction. The resin case 11 is formed in a tubular shape with one opening. Inside the resin case 11, a radial bearing 12 and a thrust bearing 13 are arranged.

Inside the radial bearing 12, a hollow rotary shaft 14 is arranged. One of the rotating shafts 14 is formed with a flange portion 14a bulging radially outward. A turbine blade 15 is attached to the outer peripheral surface of the flange portion 14a of the rotating shaft 14. The rotating shaft 14 is the cylindrical portion 1
4b is held by the radial bearing 12, and the flange portion 14a is held by the thrust bearing 13.

Inside the resin case 11, an air nozzle 16 for ejecting high-speed air toward the turbine blade 15 of the rotating shaft 14 is arranged. When high-speed air is ejected from the air nozzle 16, the rotating shaft 14 rotates at high speed around the axis. The rotating shaft 14 is used for the thrust bearing 1.
3 holds the side surface of the flange portion 14a, so that the air is ejected from the air nozzle 16 to rotate the rotary shaft 1a.
4 is prevented from shifting axially.

An external thread 14c is formed at the tip of the rotating shaft 14, and a portion connected to the external thread 14c is formed on a tapered surface 14d. Male thread 14 of rotating shaft 14
An atomizing head 20 is screwed into c. When the atomizing head 20 is completely screwed into the male screw portion 14c, the atomizing head 20 is configured to sufficiently adhere to the tapered surface 14d of the rotating shaft 14. As a result, rattling of the atomizing head 20 with respect to the rotating shaft 14 is prevented.

A partition 20a is formed on the atomizing head 20. At the center of the partition wall 20a, a conical protrusion 20b protruding toward the rotation shaft 14 is formed. Projection 20
A cleaning hole 20c penetrating the partition wall 20a is formed in b. A paint passage 20d penetrating the partition 20a is formed on the outer periphery of the partition 20a.

A hollow portion 14e extending in the axial direction of the rotating shaft 14
, A nozzle assembly 21 is disposed. Noz
The luass assembly 21 has a cleaning agent nozzle 22 arranged concentrically with the rotating shaft 14. The detergent nozzle 22 has a detergent passage 23 extending in the axial direction.
A first paint nozzle 24, a second paint nozzle 25, and a third paint nozzle 26 are inserted into the cleaning agent passage 23. Three positioning holes 23a, 23b and 23c are formed in the end wall 22a of the cleaning agent nozzle 22.

The positioning holes 23a, 23b and 23c are respectively located at three equally spaced positions in the circumferential direction. The end of the first paint nozzle 24 is inserted into the positioning hole 23a. The end of the second paint nozzle 25 is inserted into the positioning hole 23b. In the positioning hole 23c,
The end of the third paint nozzle 26 is inserted. Each of the paint nozzles 24, 25, 26 inserted into each of the positioning holes 23a, 23b, 23c has a distance S from the end wall 22a.
Only protruding.

The nozzle assembly 21 includes a cleaning agent nozzle.
The nozzle 22 and each of the paint nozzles 24, 25, 26 form three cleaning agent nozzle outlets 27. Cleaning agent
The outlet 27 is formed by a gap between the inner peripheral surface of each positioning hole 23a, 23b, 23c and the outer peripheral surface of each paint nozzle 24, 25, 26. Nozzle assembly 2
The end opposite to the atomizing head 20 has substantially the same configuration as the atomizing head 20 side.

[0020] In the end of the atomization head 20 opposite to the nozzle assembly 21, the first coating material nozzle 24 projecting from the end wall of the nozzle assembly 21, the resin case 11
Is connected to the paint passage 31 formed at the bottom. Nozzle
The second paint nozzle 2 protruding from the end wall of the assembly 21
5 is a paint passage 32 similarly formed in the resin case 11.
It is connected to the. Similarly, the third paint nozzle 26
It is connected to a paint passage 33 formed in the resin case 11. Cleaning agent passage 23 communicating with cleaning agent nozzle outlet 27
Is connected to a cleaning passage 34 formed in the resin case 11.

The paint passage 31 is connected to a first paint supply source (not shown) via a first open / close valve 51 and a paint hose 61 attached to the resin case 11. The paint passage 32 is connected to a second paint supply source (not shown) via a second open / close valve 52 and a paint hose 62 attached to the resin case 11. The paint passage 33 is connected to a third paint supply source (not shown) via a third on-off valve 53 and a paint hose 63 attached to the resin case 11. Each paint supply source has a function of pumping paint of a different color to each paint hose 61, 62, 63.

The resin case 11 is formed with a backflow prevention passage 71 one of which opens to the hollow portion 14 e of the rotary shaft 14 and the other opens to the end face of the resin case 11. A fourth opening / closing valve 72 is connected to the end face side of the resin case 11 of the backflow prevention passage 71. The fourth on-off valve 72 is connected to an air supply source (not shown) via an air hose 73. During opening of the fourth on-off valve 72, compressed air A ₁ is adapted to be supplied to the hollow portion 14e of the rotary shaft 14 from the air supply source.

The washing passage 34 is connected to an electromagnetic switching valve 81 via a fifth opening / closing valve 54 and a washing hose 64 attached to the resin case 11. Solenoid switching valve 81
Is composed of a first switching valve 82 and a second switching valve 83. The first switching valve 82 is connected to a detergent supply source (not shown) via a detergent hose 84. The second switching valve 83 is connected to an air supply source (not shown) via an air hose 85. The electromagnetic switching valve 81 is provided with the detergent P
And the compressed air A ₂ is selected and supplied to the cleaning agent passage 23. In this embodiment, a thinner is used as a cleaning agent.

Except when the atomizing head 20 is cleaned, the electromagnetic switching valve 8
So that the compressed air A ₂ is selected by opening operation of the second switching valve 83 1. Then, except when the atomizing head 20 is washed, the fifth on-off valve 54 is opened, and the cleaning agent passage 2 is opened.
It is always compressed air A ₂ are supplied to the 3.

A high voltage generator 75 for charging the paint discharged from the atomizing head 20 with static electricity is accommodated in the resin case 11. The high voltage generator 75 is connected to a power supply line 76.
Is connected to a power source (not shown). On the end face of the resin case 11 on the side of the atomizing head 20, there is provided a pattern air nozzle 77 for blowing the paint discharged from the atomizing head 20 toward an object (not shown).

Next, the method and operation of the rotary atomizing electrostatic coating will be described. In the coating line, a vehicle body, which is an object to be coated, is transported by a conveyor. When the vehicle body reaches a predetermined position, a coating operation by the rotary atomizing electrostatic coating device 10 is started. In this case, a paint color based on the specifications of the vehicle body is selected, and only the corresponding on-off valve (for example, the second on-off valve 52) is opened.

When the second on-off valve 52 is opened, the paint T is sent from the second paint supply source to the second paint nozzle 25 under pressure, and from the tip of the second paint nozzle 25, the inner wall surface of the atomizing head 20 is opened. The side is supplied with paint. Atomizing head 20 is air nozzle 16
The paint adhered to the inner wall surface of the atomization head 20 passes through the paint passage 20d, and is discharged as particles from the outer peripheral end of the atomization head 20 by centrifugal force because the air is rotated at high speed by the high-speed air from the nozzle. Is done.

The paint discharged from the atomizing head 20 is negatively charged by the high voltage generator 75. The paint particles released from the atomizing head 20 are blown off toward the workpiece by the air blown out from the pattern air nozzle 77. Therefore, the paint discharged from the atomizing head 20 is efficiently applied to the object to be coated by the suction by the electrostatic force and the pushing effect by the air from the air nozzle 77.

When the painting operation is completed, the second on-off valve 52
Is closed, and then the fifth on-off valve 54 is opened. Accordingly, the cleaning agent of the cleaning agent P is the nozzle assembly 21 Bruno
Each cleaning agent is fed under pressure through the cleaning agent passage 23 of the spill 22.
It is ejected from the nozzle outlet 27 toward the atomizing head 20. each
A part of the cleaning agent P jetted from the cleaning agent nozzle outlet 27 is also jetted to the tip side of the atomizing head 20 through the cleaning hole 20c formed in the partition wall 20a, so that the atomizing head to which the paint is supplied is provided. The inner peripheral surface of 20 is almost completely cleaned by the cleaning agent.

Further, the tip of each coating material nozzle 24, 25, and 26, since the protruded slightly from the end of the cleaning agent nozzle 22, the coating material nozzle 2 by the detergent nozzle outlet 27
It is also possible to clean the tips of 4, 25 and 26. In this case, the paint present at the tip of each of the paint nozzles 24, 25, 26 is sucked out by the ejection of the detergent from each of the detergent nozzle outlets 27. Therefore, paint nozzle 2
The paint adhering to the tips of 4, 25, and 26 can be sufficiently washed away, and the paint at the time of the previous paint dripping to the atomizing head 20 is reliably eliminated.

When cleaning the atomizing head 20, the atomizing head 20
Since the pressure in the space inside the nozzle increases, the cleaning agent P and the residual paint T may flow into the hollow portion 14e of the rotary shaft 14, but when the atomizing head 20 is washed, the fourth on-off valve 7
The compressed air A1 is supplied to the hollow portion 14e of the rotating shaft 14 by opening the valve of _{No. 2} . Therefore, the pressure in the hollow portion 14e rises of the rotating shaft 14, the cleaning agent P and the residual paint T tries to flow back into the hollow portion 14e is pushed back by the compressed air A _1, detergents P into the hollow portion 14e And the inflow of the residual paint T is reliably prevented. Therefore, the rotation shaft 14 does not become unrotatable due to the backflow of the cleaning agent P and the residual paint T.

In the coating operation by the rotary atomizing electrostatic coating apparatus 10, when coating the bottom surface of the object to be coated, it is necessary to direct the paint discharged from the atomizing head 20 upward. This kind of painting posture is called upward painting.In upward painting work, the paint discharged from the paint nozzle flows down due to gravity, and the paint that has flowed down is the detergent nozzle.
It may flow into the cleaning agent passage 23 from the outlet 27. In this embodiment, the second switching valve 83 of the electromagnetic switching valve 81
And compressed because the air A ₂ is supplied to the fifth on-off valve 54 constantly irrigation channel 23 through the paint T the pressure in the irrigation channel 23 is increased, flowing down from the paint nozzle, the pressure of the compressed air Pushed back by. Therefore, the backflow of the paint T to the cleaning agent passage 23 is prevented, and the color mixture due to the backflow of the paint is eliminated.

At the time of cleaning the atomizing head 20, the electromagnetic switching valve 81
The thinner as the cleaning agent P is supplied to the cleaning agent passage 23 by the opening operation of the first switching valve 82, but after the atomizing head 20 is cleaned, the switching operation of the electromagnetic switching valve 81 causes the cleaning agent to change. compressed air A ₂ is supplied to the passage 23. Atomization head 20
Immediately after cleaning, thinner adheres to each of the paint nozzles 24, 25, and 26. If the thinner adheres and drops during electrostatic coating, the viscosity of the paint changes and adversely affects the coating quality. by supplying compressed air a ₂ to irrigation channel 23 after washing the Kaatama 20, the coating material nozzle 24,
It becomes possible to dry the thinner adhered to 25 and 26 in a short time.

[0034]

According to the present invention, the following effects can be obtained. (1) In the rotary atomizing electrostatic coating method according to the first aspect, compressed air is supplied to the hollow portion of the rotating shaft when the atomizing head is washed, so that the inside of the hollow portion of the rotating shaft is washed when the atomizing head is washed. Can be increased, and the cleaning agent and the paint which are going to flow into the hollow portion can be pushed back. Therefore, it is possible to prevent the cleaning agent and the paint from flowing into the hollow portion of the rotating shaft at the time of cleaning the atomizing head, and it is possible to prevent the rotation shaft from being unable to rotate due to the flowing of the cleaning agent and the paint. (2) In the rotary atomizing electrostatic coating method according to the second aspect, compressed air is supplied to the cleaning agent passage except when the atomizing head is cleaned with the cleaning agent. The pressure in the inside can be increased, and it becomes possible to push back paint from a paint nozzle which tends to flow into the cleaning agent passage at the time of upward painting. Therefore, it is possible to prevent the paint from flowing into the cleaning agent passage at the time of upward coating, and to prevent color mixing due to the paint from flowing. Further, the cleaning agent attached to the coating material nozzle by washing the atomizing head, it can be dry by compressed air from the detergent communication path and become, it is possible to prevent the residual of the cleaning agent into the vicinity of the coating material nozzle. Therefore, the dripping of the cleaning agent from the vicinity of the paint nozzle during the electrostatic coating is eliminated, and a decrease in the coating quality due to the dripping of the cleaning agent can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a rotary atomizing electrostatic coating apparatus for carrying out the present invention.

FIG. 2 is an enlarged sectional view of the vicinity of a paint nozzle tip in the apparatus of FIG.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is an enlarged cross-sectional view of the vicinity of the tip of a paint nozzle during upward painting by the apparatus of FIG. 1;

FIG. 5 is a schematic configuration diagram of a conventional rotary atomizing electrostatic coating apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Rotary atomizing electrostatic coating apparatus 14 Rotating shaft 14e Hollow part 20 Atomizing head 23 Cleaning agent passage 24 Paint nozzle 25 Paint nozzle 26 Paint nozzle A ₁ Compressed air supplied to the hollow portion of the rotating shaft A ₂ Cleaning agent passage Compressed air supplied

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 60-189351 (JP, U) JP-A 5-63656 (JP, U) JP-B-58-44032 (JP, B2) JP-B 5-5- 9145 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) B05D 1 / 02,1 / 04 B05B 5 / 04,5 / 08 B05B 15/02

Claims (2)

(57) [Claims] 1. A rotary atomizing electrostatic coating in which a plurality of paint nozzles and a cleaning agent passage for cleaning an atomizing head attached to a tip of the rotary shaft are disposed in a hollow portion of the rotary shaft. A rotary atomizing electrostatic coating method using a device, wherein compressed air is supplied to a hollow portion of a rotary shaft when the atomizing head is washed with a cleaning agent discharged from the cleaning agent passage. Atomization electrostatic coating method. 2. A rotary atomizing electrostatic coating in which a plurality of paint nozzles and a cleaning agent passage for cleaning an atomizing head attached to a tip of the rotary shaft are disposed in a hollow portion of the rotary shaft. A rotary atomizing electrostatic coating method using an apparatus, wherein compressed air is always supplied to the cleaning agent passage except when the atomizing head is cleaned with a cleaning agent. Method.