JP2598769B2 - Rotary atomizing electrostatic coating equipment - 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 type electrostatic coating apparatus suitable for spraying a water-based paint or a solvent-based paint on an object to be coated such as a vehicle body.

[0002]

2. Description of the Related Art FIGS. 3 to 6 show a rotary atomizing type electrostatic coating apparatus according to the prior art.

In FIG. 1, reference numeral 1 denotes an electrostatic coating machine, and 2 denotes a main body made of a metal cylinder constituting a housing of the electrostatic coating machine 1. An annular motor holder 2A is provided at the tip end of the main body 2. Are integrally formed, and a mounting bracket (not shown) is provided on the base end side. Further, an outer peripheral side of the main body 2 is covered with a main body cover 3, and an external electrode used to charge a low electric resistance paint such as a water-based paint or a metallic paint on the outer surface side of the main body cover 3. (Not shown) is provided.

[0004] Reference numeral 4 denotes a turbine type air motor mounted on a motor holder 2A of the main body 2, and the air motor 4 comprises:
Hydrostatic air is provided from a shaft hole 5 drilled in the axial direction, air bearings 6 and 6 provided to surround the shaft hole 5, and a turbine motor 7 provided at the base end side of the shaft hole 5. It is constituted also as a bearing. Air is supplied to each air bearing 6 through a bearing air supply passage 8, and the turbine motor 7
Is supplied with air through a drive air supply passage 9.

[0005] Reference numeral 10 denotes a hollow cylindrical rotary shaft inserted through the shaft hole 5.
, And the front end projects outside the air motor 4.
The rotating shaft 10 is driven to rotate while being supported by each air bearing 6 by a turbine motor 7.

Reference numeral 11 denotes a rotary shaft 1 located outside the air motor 4.
4 shows a bell-shaped rotary atomizing head fixed to the tip side of the rotary shaft, and the rotary atomizing head 11 is attached to the rotary shaft 10 at one end with an intermediate rim 11A in the axial direction as shown in FIG. Part 11B, and the other end side spreads like a bosh.
1C, the leading end side of the smoothing surface 11C is a discharge edge 11D in which a number of V-shaped grooves are formed.

Reference numeral 12 denotes a hub member provided in the middle of the smoothing surface 11C of the rotary atomizing head 11, and the hub member 12 is
The rear side has a convex conical paint supply surface 1 to which paint, a cleaning solvent, and the like are selectively supplied from a feed tube 20 described later.
2A, a large number of first hub holes 12B are formed in the outer peripheral side for guiding the paint and the cleaning solvent from the paint supply surface 12A to the discharge end edge 11D side of the rotary atomizing head 11 (only two are shown). In addition, a second hub hole 12C for supplying a thinner as a cleaning solvent is formed on the front side at the center.

Reference numeral 13 denotes an inner air nozzle provided on the distal end side of the main body 2 so as to surround the outer periphery of the rotary atomizing head 11;
Indicates outer air nozzles provided outside the inner air nozzle 13. The outer air nozzle 14 is screwed to the main body cover 3 and the inner air nozzle 13 is connected to the main body 2.
And sandwiched between. In addition, each of the air nozzles 13, 1
4, an annular air ejection hole 15 is formed, and when the air from the shaping air supply passage 16 is supplied through the air chambers 17, 18, the air ejection hole 15 is formed. Rotating atomizing head 11 as shaping air
To form a coating pattern of the paint sprayed from the rotary atomizing head 11 into a circular shape. Another annular air ejection hole 19 is also formed between the rotary atomizing head 11 and the inner air nozzle 13, and the air ejection hole 19 is a part of the air flowing out of each air bearing 6, the turbine motor 7, and the like. The part is blown out as shaping air.

Reference numeral 20 denotes a feed tube provided coaxially within the rotating shaft 10, reference numeral 21 denotes an outer tube which constitutes the feed tube 20 together with an inner tube 22, which will be described later.
The base end is attached to the main body 2, and the distal end is reduced in diameter and extends to a position corresponding to the rim 11 </ b> A of the rotary atomizing head 11. Reference numeral 22 denotes an inner cylinder disposed coaxially within the outer cylinder 21. The inner cylinder 22 has a base end attached to the main body 2,
The distal end is reduced in diameter and protrudes to the outside of the outer cylinder 21, and a valve seat 22A on which a valve body 25C of a paint valve 25 to be described later is detached and seated halfway.
Are integrally formed.

Reference numeral 23 denotes a paint passage formed in the inner cylinder 22. The paint passage 23 has a base end connected to a paint supply pipe 32 to be described later, and a tip end directed toward the paint supply surface 12A of the hub member 12. Open. A paint valve 25 is provided in the middle of the paint passage 23. The paint valve 25 is opened and closed by the paint valve 25 so that the paint contained therein is ejected toward the hub member 12.

Reference numeral 24 denotes a solvent passage formed between the outer cylinder 21 and the inner cylinder 22. The solvent passage 24 has a base end connected to a solvent supply pipe 35 described later, and a tip end connected to the inner cylinder 22.
It is open toward the front end side. The solvent passage 24
A tip-side cleaning valve 26, which will be described later, is provided in the middle, and is opened and closed by the tip-side cleaning valve 26 to inject thinner supplied from the outside toward the distal end side of the inner cylinder 22. is there.

Reference numeral 25 denotes a paint valve comprising a pneumatic switching valve having two ports and two positions. The paint valve 25 has an actuator 25A provided on the main body 2 and the actuator 2A at the base end.
5A, a valve shaft 25B having a distal end inserted through the inner cylinder 22 and an inner cylinder 22 provided at the distal end of the valve shaft 25B.
And a valve body 25C which is detachably seated on the valve seat 22A. When the control air from the outside is supplied to and discharged from the actuator 25A, the paint valve 25 expands and contracts the valve shaft 25B to cause the valve body 25C to be separated from and seated on the valve seat 22A of the inner cylinder 22, and the paint passage 23 It opens and closes.

Numeral 26 designates a tip-side cleaning valve comprising a two-port, two-position spring return type pneumatic switching valve. The tip-side cleaning valve 26 is an actuator 26 provided on the main body 2.
A, a valve shaft 26B having a proximal end connected to the actuator 26A and a distal end inserted into the solvent passage 24, and a valve provided at the distal end of the valve shaft 26B for opening and closing the middle of the solvent passage 24. And a body 26C. And
The front end side cleaning valve 26 is opened and closed by control air from the outside, and thereby communicates and shuts off between a cleaning valve device 34 described later and the solvent passage 24.

Further, in FIG. 5, reference numeral 27 denotes a drain passage formed in the main body 2, and one end of the drain passage 27 is provided outside the electrostatic coating machine 1 through a drain pipe 28. The other end is connected to the middle of the paint passage 23 in the main body 2. Reference numeral 30 denotes a drain valve provided in the middle of the drain passage 27, and the drain valve 30
Is configured as a spring return type pneumatic switching valve having two ports and two positions almost similarly to the front end side cleaning valve 26. The drain valve 30 is opened and closed by control air from the outside to open and close the drain passage 27 and the waste tank 29.

Reference numeral 31 denotes a color changing valve device provided outside the electrostatic coating machine 1.
2 is connected to the paint passage 23 via a gear pump 33 provided in the middle of the paint supply pipe 32. The color changing valve device 31 includes a plurality of paints (2, A, B,...).
(Only the colors are shown), water, thinner, and air are selectively discharged and supplied into the paint passage 23.

Reference numeral 34 denotes the electrostatic coating machine 1 together with the color changing valve device 31.
3 shows a cleaning valve device provided outside the washing valve device.
Numeral 4 is connected to the tip-side cleaning valve 26 via a solvent supply pipe 35 and to the solvent passage 24 via the tip-side cleaning valve 26. The cleaning valve device 34 selectively discharges a thinner for cleaning the front end side of the inner cylinder 22 and air for discharging the thinner toward the front side of the rotary atomizing head 11, It is supplied to the solvent passage 24.

The rotary atomizing type electrostatic coating apparatus according to the prior art has the above-mentioned configuration. Next, the operation of the electrostatic atomizing apparatus will be described with reference to FIG.

First, a washing process and a A-color supply process are performed after the end of the previous color coating, and the A-color paint is filled from the paint supply pipe 32 to the paint passage 23 and the rotary atomizing head 11.

In the A-color coating process, the rotary shaft 10 and the rotary atomizing head 11 are rotated by the air motor 4.
On the other hand, while applying a high voltage to the external electrode, the shaping air is supplied from the shaping air supply passage 16, and the shaping air is ejected from the air ejection hole 15 to the front side of the rotary atomizing head 11. Next, the paint valve 25 is switched to the switching position (a).
When the valve is switched to the switching position (b) and the valve is opened, the A-color paint in the paint passage 23 becomes the paint supply surface 12A of the hub member 12.
And is atomized by the high-speed rotation of the rotary atomizing head 11. The atomized A-color paint is charged while passing through the corona discharge region by the external electrode,
The coating pattern is formed by the shaping air from the air ejection holes 15 and 19, and is applied to the object by flying along the lines of electric force generated between the external electrodes and the object.

Next, when the painting process of the color A is completed and the next color paint, for example, the paint of the water-based color B is sprayed, the paint remains on the paint supply pipe 32, the paint passage 23, the hub member 12 and the like. The washing process of washing the A-color paint is performed.

That is, in the cleaning process, the drain valve 30 is switched from the switching position (a) to the switching position (b) to open the valve, and the drain passage 27 and the waste tank 29 are connected, as shown in FIG. As described above, water, air, and thinner are alternately discharged from the color changing valve device 31 a plurality of times. As a result, the A-color paint remaining in the paint supply pipe 32, the paint passage 23 and the like flows into the waste liquid tank 29 from the drain passage 27 through the drain pipe 28 and is collected. When the washing of the paint passage 23 and the like is completed, the paint valve 25 is switched to the switching position (b) to open the valve, and the thinner from the color changing valve device 31 is supplied into the paint passage 23. As a result, the thinner is moved from the paint passage 23 to the hub member 12.
Is sprayed to the side of the paint supply surface 12A to clean the tip side of the paint passage 23, the rotary atomizing head 11, the hub member 12, and the like.

Here, in the A-color coating process, the A-color paint adheres to the outer periphery of the distal end of the inner cylinder 22 due to turbulence or the like when the paint is ejected, and as shown in FIG. Paint 36 results. However, in the above-described cleaning process, since only thinner or the like is sprayed from the paint passage 23 toward the rotary atomizing head 11, the attached paint 36 cannot be washed. Therefore, in the cleaning step, in addition to the main cleaning of the paint passage 23 and the like described above, as shown in FIG.
Auxiliary cleaning for spot-wise cleaning of the outer peripheral side of the tip 2 is performed.

That is, the tip side cleaning valve 26 is switched to the switching position (a).
To the switching position (b) to open the valve and discharge the thinner from the cleaning valve device 34. As a result, the thinner is supplied to the solvent passage 24 from the solvent supply pipe 35 and is discharged from the solvent passage 24 to the outer peripheral side of the distal end of the inner cylinder 22 to wash the adhered paint 36. When the cleaning of the adhered paint 36 is completed, air is supplied from the cleaning valve device 34 into the solvent passage 24, and the thinner remaining in the solvent passage 24 is discharged into the coating booth by the air.

Finally, in the case of performing the B-color coating subsequent to the A-color coating, the color changing valve device 3 with the drain valve 30 opened.
1 supplies the B color paint into the paint passage 23 and the drain passage 27, then closes the drain valve 30 and opens the paint valve 25 for a short time. After the color paint is supplied and the preparation of the coating of the B color is performed, the coating of the object to be coated with the B color is started.

[0025]

In the above-described rotary atomizing type electrostatic coating apparatus according to the prior art, the feed tube 20 is formed of an outer cylinder 21 and an inner cylinder 22 in a double pipe structure. By forming a solvent passage 24 independent of the paint passage 23 in the tube 20, an auxiliary washing separate from the main washing is performed to wash the attached paint 36 generated on the outer peripheral side of the distal end of the inner cylinder 22 to improve the coating quality. We are improving. Here, if the thinner in the solvent passage 24 is left at the end of the auxiliary cleaning, at the time of the next coating, the remaining thinner is mixed into the paint, thereby causing a problem such as impairing the coating quality.

Therefore, in the prior art, at the end of the auxiliary cleaning, the thinner remaining in the solvent passage 24 is discharged into the coating booth by the air from the cleaning valve device 34. However, in this case, all the residual thinner from the cleaning valve device 34 to the tip of the solvent passage 24 is discharged into the external coating booth. Not only consumes a large amount of water but also contaminates a painting booth as an external environment. In particular, recently, from the viewpoint of environmental protection, reduction of pollution by thinners and the like has been demanded from various industries. However, with the conventional technology, such demands cannot be satisfied, and reliability and performance are low. There's a problem.

The present invention has been made in view of the above-mentioned problems of the prior art. At the end of washing, the washing solvent remaining in the solvent passage can be collected in a waste liquid tank and reliably removed. It is an object of the present invention to provide a rotary atomizing electrostatic coating device capable of preventing contamination of an external environment such as a booth.

[0028]

To solve the above-mentioned problems, the present invention employs a feature that the cleaning solvent remaining in the solvent passage at the end of the washing is sucked into the solvent passage and the inside of the waste liquid tank is removed. That the suction means for discharging the water is provided.

[0029]

When the washing process is completed, the suction means sucks the washing solvent remaining in the solvent passage and discharges it into the waste liquid tank to remove it.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those in the prior art shown in FIGS. 3 to 6 are denoted by the same reference numerals, and description thereof will be omitted.

In the drawing, reference numeral 41 denotes a cleaning valve device according to the present embodiment. The cleaning valve device 41 is substantially the same as the cleaning valve device 34 described in the prior art, and the solvent supply pipe 35 and the front-end cleaning valve 2 are provided.
The thinner is connected to the solvent passage 24 through a cleaning passage 6 and the like.
However, the cleaning valve device 41 is provided with a discharge valve 42 composed of, for example, a spring return type air type switching valve, instead of the air valve of the cleaning valve device 34 described in the related art. Further, the discharge valve 42 is connected to an ejector 44 described later via a discharge pipe 43. And the discharge valve 4
Reference numeral 2 denotes a valve which is opened and closed by control air from the outside, thereby connecting and disconnecting the solvent supply pipe 35 and the discharge pipe 43.

Reference numeral 44 denotes an ejector as a suction pump. The ejector 44 is provided in the main passage 44A in the waste liquid tank 2.
The thinner in the discharge pipe 43 is sucked using the flow of a fluid such as air flowing toward the nozzle 9, and the thinner is discharged into the waste liquid tank 29. Thus, the suction mechanism 45 as a suction means, which is a constituent element of the present invention, includes the discharge valve 42, the discharge pipe 43, and the ejector 44.

The rotary atomizing type electrostatic coating apparatus according to the present embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art. Therefore, a cleaning process, which is a feature of the rotary atomizing electrostatic coating apparatus according to the present embodiment, will be described with reference to FIG.

First, when one coating with the water-based A-color paint is completed, the adhesion paint 36 generated on the inner cylinder 22 during the interval time T until the next A-color coating process starts.
First auxiliary cleaning is performed in order to remove. That is, by closing the paint valve 25 and opening the front-end side cleaning valve 26, discharging the thinner from the cleaning valve device 41 into the solvent supply pipe 35, and supplying the thinner into the solvent passage 24, The outer peripheral side of the distal end of the inner cylinder 22 is cleaned.

At substantially the same time as the discharge of thinner from the cleaning valve device 41, the discharge valve 42 is opened, and the ejector 4 is opened.
Activate 4 As a result, the thinner remaining in the solvent passage 24 is sucked into the ejector 44 via the tip-side cleaning valve 26, the solvent supply pipe 35, the discharge valve 42, and the discharge pipe 43, and is discharged from the ejector 44 into the waste liquid tank 29. Is discharged. The tip side cleaning valve 26, the discharge valve 42, and the ejector 44 are closed and stopped after a predetermined time t has elapsed from the end of the thinner discharge from the cleaning valve device 41. Here, the predetermined time t is set such that only the thinner between the tip side (the rotary atomizing head 11 side) of the solvent passage 24 and the tip side cleaning valve 26 is discharged to the waste liquid tank 29. Is set to be substantially equal to the time required for the thinner located at the position to pass through the front-end-side cleaning valve 26 by suction by the ejector 44.

Next, in the cleaning process performed between the A-color coating process and the B-color coating process, the cleaning (main cleaning) of the paint passage 23 using thinner, air, and water from the color changing valve device 31 is performed. At the same time, as shown in FIG. 2, a second auxiliary cleaning substantially the same as the first auxiliary cleaning described above is performed.

Thus, according to the present embodiment, the first and second auxiliary cleanings are performed at the time of painting the same color and at the time of color change. In each of the auxiliary cleanings, the thinner from the cleaning valve device 41 is moved to the front end side. The solvent is supplied into the solvent passage 24 through the washing valve 26 and the like,
In addition, the paint thinner 36 formed on the tip side of the solvent passage 24 is effectively removed, and at the end of washing, the residual thinner in the solvent passage 24 located between the tip end side of the solvent passage 24 and the tip side cleaning valve 26 is removed by the suction mechanism 45. , And can be reliably collected in the waste liquid tank 29.

As a result, it is possible to reliably prevent the residual thinner in the solvent passage 24 from being discharged to the coating booth. Therefore, it is possible to effectively prevent the paint booth from being contaminated by the residual thinner, thereby protecting the environment. it can.

Further, only the thinner remaining from the leading end of the solvent passage 24 to the leading end cleaning valve 26 is collected in the waste liquid tank 29, and the thinner in the solvent supply pipe 35 is left as it is. Since the thinner of the cleaning valve device 41 can be efficiently consumed, the cleaning cost can be greatly reduced, and the thinner can be quickly supplied to the solvent passage 24 at the next cleaning, thereby shortening the cleaning time. can do.

Further, since the first auxiliary cleaning is performed even during the interval time T during the coating of the same color, thinner can be sprayed before the paint adhered to the inner cylinder 22 dries. The adhering paint can be removed.

In the above-described embodiment, the suction mechanism 45 as the suction means is described as being constituted by the ejector 44 and the like as the suction pump. However, instead of this, another mechanism such as a reciprocating vacuum pump may be used. You may comprise using a suction pump.

In the above embodiment, the cleaning valve 26 on the front end side is used.
Has been described as being provided in the main body 2, but instead, for example, a configuration in which the distal end side cleaning valve 26 is provided outside the main body 2 may be adopted.

Further, in the above-described embodiment, the tip-side cleaning valve 2
6, the discharge valve 42 and the ejector 44
Although it has been described that the operation is time-controlled by the predetermined time t, the present invention is not limited to this. For example, only the opening time of the discharge valve 42 is time-controlled based on the predetermined time t, and the operation time of the ejector 44 is Alternatively, the control may be performed with a long operation time T (T> t) extending around the opening time (predetermined time t) of the discharge valve 42. In this case, since the ejector 44 generates a predetermined negative pressure when the discharge valve 42 opens, the thinner in the solvent passage 24 can be quickly sucked. In some cases, the ejector 44 may be continuously operated without being stopped, and the suction of the thinner may be controlled by the discharge valve 42.

In the above-described embodiment, a coating apparatus using a bell-shaped rotary atomizing head has been exemplified as the rotary atomizing type electrostatic coating apparatus. Instead, a disk type rotary atomizing head is used. It may be applied to a painted coating apparatus.

Further, in the above embodiment, the case where a water-based paint is used has been described as an example. However, the present invention is not limited to this, and a solvent-based paint may be used.

[0046]

As described above in detail, according to the present invention, the solvent passage is provided with suction means for sucking the cleaning solvent remaining in the solvent passage at the end of cleaning and discharging the cleaning solvent into the waste liquid tank. Therefore, it is possible to reliably prevent the residual thinner in the solvent passage from being discharged to a coating booth or the like as an external environment at the end of the cleaning. As a result, contamination of the interior of the coating booth by the residual thinner can be effectively prevented, environmental protection can be achieved, and reliability and safety can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an entire configuration of a rotary atomizing type electrostatic coating apparatus according to an embodiment of the present invention.

FIG. 2 is a process explanatory diagram showing a painting process, a cleaning process, and the like.

FIG. 3 is a longitudinal sectional view showing a main part of an electrostatic coating machine of a rotary atomizing type electrostatic coating apparatus according to the prior art.

FIG. 4 is an enlarged longitudinal sectional view showing a main part in FIG. 3;

FIG. 5 is a circuit diagram showing the entire configuration of the rotary atomizing electrostatic coating apparatus.

FIG. 6 is a process explanatory diagram showing a painting process and a cleaning process.

[Explanation of symbols]

 2 Body 4 Air motor 10 Rotary shaft 11 Rotary atomizing head 20 Feed tube 21 Outer tube 22 Inner tube 23 Paint passage 24 Solvent passage 29 Waste liquid tank 45 Suction mechanism (suction means)

Claims (1)

(57) [Claims] 1. A cylindrical main body, an air motor provided in the main body, a rotary shaft inserted in an axial direction of the air motor and rotated by the air motor, A rotary atomizing head provided on the tip side,
A feed tube comprising an outer cylinder and an inner cylinder coaxially provided in the rotary shaft, and a tip side extending into the rotary atomizing head, and formed in the inner cylinder of the feed tube;
A paint passage through which cleaning solvent and air are selectively supplied;
Formed between an outer cylinder and an inner cylinder of the feed tube,
In a rotary atomizing electrostatic coating apparatus comprising a solvent passage to which a cleaning solvent is supplied, suction for discharging the cleaning solvent remaining in the solvent passage at the end of the cleaning and discharging the cleaning solvent into a waste liquid tank into the solvent passage. A rotary atomizing type electrostatic coating apparatus characterized by comprising means.