JP3658086B2 - Electrostatic coating method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic coating method and apparatus for performing electrostatic coating by supplying conductive paint to a coating gun via a paint supply path.
[0002]
[Prior art]
Generally, an electrostatic coating apparatus using a conductive paint is supplied with a conductive paint from a paint supply source through a paint supply path to a paint gun, and the conductive paint is in a state where a high voltage is applied. By being derived from the coating gun, the workpiece is electrostatically coated.
[0003]
In this type of electrostatic coating apparatus, it is necessary to prevent high-voltage leakage, and various measures against insulation have been conventionally taken. For example, an electrostatic coating apparatus disclosed in JP-A-4-63156 is known. In this prior art, the paint supply pipe is detachable from the input port side connection port of the reciprocating pump. Then, after the paint is introduced from the paint supply pipe to the reciprocating pump, the paint supply pipe is separated from the input port side connection port, and is electrically insulated so that a high voltage is applied from the reciprocating pump. Is supplied to the workpiece.
[0004]
[Problems to be solved by the invention]
However, in the above prior art, since the paint supply pipe and the input port side connection port are engaged and disengaged every time the paint supply operation is performed, the connection portion between the paint supply pipe and the input port side connection port is provided. Air tends to remain. Therefore, when the paint supply pipe and the input port side connection port are connected and the paint supply operation is performed from the paint supply pipe, there is a possibility that the air remaining in the connection portion is sent to the reciprocating pump together with the paint. Accordingly, it has been pointed out that air bubbles are mixed in the coating film formed on the workpiece, and the coating quality is remarkably deteriorated.
[0005]
The present invention solves this type of problem, and provides an electrostatic coating method and apparatus that can reliably remove air at a connected portion and can efficiently perform a high-quality coating operation. With the goal.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is configured to connect the first supply path unit communicating with the paint supply source and the second supply path unit to which a high voltage is applied, to the second supply path unit. The second on-off valve provided is closed, and the third on-off valve provided on the branch path provided upstream of the second on-off valve and connected to the cleaning medium supply source is opened, while the branch path is opened. The arranged fourth on-off valve is closed. In this state, when the first on-off valve disposed in the first supply path portion is opened, the connecting portion between the first and second supply path portions is pressed under the pressing action of the conductive paint sent from the paint supply source. The remaining air is pushed out between the third on-off valve and the fourth on-off valve.
[0007]
As a result, air can be reliably removed from the connecting portion of the first and second supply path portions, and then the third on-off valve is closed while the second on-off valve is opened, so that no air is present. It becomes possible to supply a good conductive paint to the coating gun side.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration explanatory diagram of an electrostatic coating apparatus 10 according to an embodiment of the present invention.
[0009]
The electrostatic coating apparatus 10 includes a grounded color change valve mechanism 12 that selectively supplies a plurality of different paints, a paint gun 14 that injects the paint onto a workpiece (not shown), the color change valve mechanism 12, and the An intermediate reservoir 16 interposed between the coating gun 14 and a paint supply path 18 provided between the intermediate reservoir 16 and the color change valve mechanism 12 communicates with the color change valve mechanism 12. The first supply path 18a and the second supply path 18b to which a high voltage is applied are electrically connected and separated, and the dump path 20 is connected to the first dump path 20a on the high voltage side and the other second A connection mechanism 22 that is electrically connected to and separated from the dump path portion 20b is provided.
[0010]
The color change valve mechanism 12 includes a first cleaning valve 24 that controls supply of air (A), water (W), cleaning liquid (S), and the like, and a plurality of paint valves 26a to 26n that can supply different paints. And.
[0011]
The connection mechanism 22 includes a fixed block (second connection part) 28 connected to the intermediate storage tank 16 via the application-side second supply path part 18b, and a non-application-side first supply path to the color change valve mechanism 12. And a movable block (first connecting portion) 30 connected via the portion 18a. The movable block 30 is connected to a rod 34 that extends from an air cylinder 32 that is a driving means, and is movable forward and backward in the direction of arrow A.
[0012]
The movable block 30 is provided with first and second male valve elements 36 and 38. As shown in FIG. 2, a first through hole 40 communicating with the first supply path portion 18 a is formed in the first male valve body portion 36, and an X1 on-off valve (first valve) is formed in the first through hole 40. On-off valve) 42 is provided. A first cleaning path 44 is formed in the second male valve body 38, and the first cleaning path 44 is integrated with the second and third cleaning paths 46 and 48 branched from the first through hole 40. And communicated with the second dump path 20b. In the first to third cleaning paths 44, 46, and 48, an X2 on-off valve 50, an X3 on-off valve 52, and an X4 on-off valve 54 are disposed, respectively.
[0013]
The fixed block 28 is provided with first and second female valve body portions 56 and 58. As shown in FIG. 2, the first female valve body portion 56 has a second supply path portion 18b. A second through hole 60 communicating with the second through hole 60 is provided, and a Y1 on-off valve (second on-off valve) 62 is disposed in the second through hole 60. A first dump path portion 20a is provided in the second female valve body portion 58, and a Y2 on-off valve 64 is disposed in the first dump path portion 20a.
[0014]
A first branch path 68 connected to a second cleaning valve 66 serving as a cleaning medium supply source is provided on the upstream side of the Y1 on-off valve 62, and branches from the first branch path 68 on the downstream side of the Y2 on-off valve 64. The formed second branch path 70 is provided. A Y3 on-off valve 72 is connected to the second branch path 70, while a Y4 on-off valve (third on-off valve) 74 and a Y5 on-off valve (fourth) are spaced apart from each other along the first branch path 68 by a predetermined distance. On-off valve) 76 is disposed.
[0015]
As shown in FIG. 1, the intermediate storage tank 16 includes a cylinder 80 in which a piston 82 is slidably reciprocated in the direction of arrow A. A paint filling cylinder chamber 84 is formed by the inner wall of the cylinder 80 and the tip of the piston 82. The cylinder wall 86 is formed with an injection hole portion 88 that is located at the inner peripheral edge of the cylinder wall 86 and communicates with the second supply path portion 18b. A hole 90 is provided.
[0016]
A ball screw 96 connected to a rotation shaft 94 of a servo motor 92 is connected to the piston 82. A cascade 98 is disposed adjacent to the cylinder 80, and this cascade 98 is connected to the low voltage supply source 100.
[0017]
As shown in FIG. 2, the coating gun 14 includes a supply path 106 that connects the paint discharge port 104 of the rotary atomizing head 102 and the second supply path portion 18 b, and a dump path 20 that is branched from the supply path 106. Is provided. A trigger valve 108 is connected to the supply path 106, while a dump valve 110 is connected to the dump path 20. As shown in FIG. 1, a third cleaning valve 112 for cleaning the rotary atomizing head 102 is connected to the coating gun 14 via a cleaning path 114.
[0018]
The operation of the electrostatic coating apparatus 10 configured as described above will be described below in relation to the electrostatic coating method according to the present embodiment.
[0019]
When performing color change coating using a paint of a different color, first, as shown in FIG. 2, electrostatic coating is performed by applying a high voltage to the previous color paint filled in the intermediate storage tank 16. While being performed (this operation will be described later), a color change cleaning operation is performed on the first supply path portion 18a side on the non-application side.
[0020]
That is, the area from the first supply path 18a to the movable block 30 is cleaned via the first cleaning valve 24 constituting the color change valve mechanism 12, and the cleaning liquid used for this cleaning is discharged together with the residual paint. The liquid is discharged from the second dump path 20b under the opening action of the X4 on-off valve 54. Next, with the X4 opening / closing valve 54 closed, new paint is supplied to the first supply path 18a from any one of the paint valves 26a to 26n (see FIG. 2).
[0021]
Therefore, when the movable block 30 moves in the direction of arrow A1 (see FIGS. 1 and 2) under the action of the air cylinder 32 constituting the connection mechanism 22, the first and second male valve elements 36 and 38 are fixed. The first and second female valve body portions 56 and 58 of the block 28 are joined. Then, as shown in FIG. 3, the X2 on-off valve 50, the Y1 on-off valve 62, the Y2 on-off valve 64, the Y4 on-off valve 74, the Y5 on-off valve 76, and the dump valve 110 are opened.
[0022]
For this reason, the cleaning water and air led out from the second cleaning valve 66 are sequentially supplied to the second supply path portion 18 b through the first branch path 68 and the second through hole 60. Water and air are sequentially introduced into the cylinder chamber 84 from the injection hole 88 of the cylinder 80 constituting the intermediate storage tank 16, and after the inside of the cylinder chamber 84 is cleaned, it is introduced into the coating gun 14 from the discharge hole 90. The Water and air are further sent from the supply path 106 in the coating gun 14 to the first dump path part 20a constituting the dump path 20, and the second male valve body part 38 and the second female valve body part 58 are connected to each other. It is discharged from the first cleaning path 44 to the second dump path section 20b through the connecting portion.
[0023]
As a result, the previous color paint remaining in the path from the fixed block 28 on the high voltage application side to the coating gun 14 is washed away. At that time, the trigger valve 108 is driven to open and close, so that the entire supply path 106 that reaches the paint discharge port 104 of the rotary atomizing head 102 is appropriately cleaned.
[0024]
Next, as shown in FIG. 4, the X1 release valve 42, the X2 release valve 50, the Y1 release valve 62, the Y2 release valve 64, and the dump valve 110 are opened. Accordingly, the next color paint supplied to the first supply path portion 18 a is supplied from the first through hole 40 to the second supply path portion 18 b via the second through hole 60, and the cylinder chamber of the intermediate storage tank 16. After filling the tip end side of 84, it is sent from the supply path 106 to the first dump path section 20a and the second dump path section 20b, and the air in the path is vented.
[0025]
Thereafter, the Y2 on-off valve 64 and the dump valve 110 are closed and the servo motor 92 is driven, and the piston 82 moves integrally with the ball screw 96 in the direction of the arrow A2 (in FIG. 4, from the position of the two-dot chain line to the solid line). See location). As a result, the cylinder chamber 84 is filled with the next color paint.
[0026]
After the intermediate color storage tank 16 is filled with the next color paint, the first and second male valve body portions 36 and 38 which are the connection portions of the fixed block 28 and the movable block 30 constituting the connection mechanism 22 and the first and second The connecting portion with the second female valve body portions 56 and 58 is washed. That is, as shown in FIG. 5, the X2 on-off valve 50, the X3 on-off valve 52, the Y3 on-off valve 72, the Y4 on-off valve 74, and the Y5 on-off valve 76 are opened, and the first branch path 68 and the first Water and air are sequentially supplied to the bifurcated path 70.
[0027]
The water and air supplied to the first branch path 68 wash the connecting portion between the first male valve body portion 36 and the first female valve body portion 56 and then from the second cleaning path 46 to the second dump path. It is discharged to the part 20b. On the other hand, the water and air supplied to the second branch path 70 are washed from the first washing path 44 to the second after washing the connecting portion between the second male valve body 38 and the second female valve body 58. It is discharged to the dump path 20b.
[0028]
When the connection mechanism 22 is cleaned, all the open / close valves including the X2 open / close valve 50 opened at the time of cleaning shown in FIG. 5 are closed. Then, the movable block 30 moves in the direction of the arrow A2 under the driving action of the air cylinder 32, and the movable block 30 is separated from the fixed block 28 with an insulation distance (see FIGS. 1 and 6).
[0029]
Next, the servo motor 92 is driven and the trigger valve 108 is opened while the low voltage supply source 100 is driven and a high voltage is applied to the paint filled in the cylinder chamber 84. Thereby, the paint in the cylinder chamber 84 is applied to a workpiece (not shown) from the paint discharge port 104 of the rotary atomizing head 102 of the coating gun 14 in a state where a high voltage is applied, and electrostatic coating is performed.
[0030]
When the electrostatic painting work is performed using the same color paint after the painting work shown in FIG. 6 is completed, the movable block 30 is moved in the direction of the arrow A1 under the driving action of the air cylinder 32. Are joined to the fixed block 28. At that time, air tends to remain in the connecting portion between the first male valve body portion 36 and the first female valve body portion 56 due to their contact and separation.
[0031]
Therefore, in the present embodiment, as shown in FIG. 7, the trigger valve 108 is closed and the Y4 on-off valve 74 is opened while the Y1 on-off valve 62 is closed, while the Y5 on-off valve 76 is closed. . Further, when the X1 opening / closing valve 42 is opened, the paint sent from the color change valve mechanism 12 is first supplied from the Y4 opening / closing valve 74 to the first branch path 68 before being supplied to the second supply path portion 18b. Part and the second branch path 70 are introduced.
[0032]
Accordingly, the air remaining at the connection portion between the first male valve body portion 36 and the first female valve body portion 56 is subjected to the pressing action of the paint sent from the first supply path portion 18a, and thus the first branch path 68. Forcibly pushed to the side, that is, between the Y4 on-off valve 74 and the Y5 on-off valve 76.
[0033]
As a result, as shown in FIG. 8, the Y4 on-off valve 74 is closed, while the X1 on-off valve 42 and the Y1 on-off valve 62 are opened, the piston 82 moves in the direction of the arrow A2 via the servo motor 92. As a result, the intermediate storage tank 16 is filled with a good paint not mixed with air through the first and second supply path portions 18a and 18b.
[0034]
After the intermediate color storage tank 16 is filled with the same color paint, the X1 on-off valve 42 and the Y1 on-off valve 62 are closed and the X3 on-off valve 52, the Y4 on-off valve 74, and the Y5 on-off valve 76 are closed as shown in FIG. Is released. For this reason, water and air are sequentially supplied to the first branch path 68 under the action of the second cleaning valve 66, and the first male valve body portion 36 and the first female valve body portion 56 through which the paint has passed are connected. The part is cleaned, and the drainage is discharged to the second dump path 20b through the second cleaning path 46.
[0035]
Further, after the X3 on-off valve 52, the Y4 on-off valve 74, and the Y5 on-off valve 76 are closed, the movable block 30 is separated from the fixed block 28 via the air cylinder 32. In this state, as shown in FIG. 6, electrostatic coating with the same color paint is performed under the opening action of the trigger valve 108.
[0036]
At that time, air is not mixed in the paint filled in the intermediate storage tank 16 from the first supply path portion 18a, and it is ensured that bubbles are mixed in the paint film electrostatically coated through the paint. Can be prevented. Thereby, in this embodiment, the effect that a high quality coating operation is efficiently performed with a simple configuration is obtained.
[0037]
In order to push the air remaining at the connecting portion between the first male valve element 36 and the first female valve element 56 toward the first branch path 68, a Y4 on-off valve 74 and a Y5 on-off valve 76 are provided. However, three or more on-off valves may be arranged in order to set various sections for accommodating air.
[0038]
【The invention's effect】
As described above, in the electrostatic coating method and apparatus according to the present invention, the air remaining at the connecting portion of the first and second supply path portions is branched under the pressing action of the conductive paint sent from the paint supply source. After being pushed out between the third on-off valve and the fourth on-off valve provided in the above, it becomes possible to supply a good conductive paint without air to the coating gun side. Thereby, it is possible to reliably prevent bubbles from being mixed in the electrostatically coated film, and a high-quality coating operation can be efficiently performed with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electrostatic coating apparatus according to an embodiment of the present invention.
FIG. 2 is a circuit explanatory diagram of the electrostatic coating apparatus.
FIG. 3 is an explanatory diagram of a circuit when cleaning a path on a high voltage application side.
FIG. 4 is an explanatory diagram of a circuit when air is extracted from a path in order to fill a paint of the next color.
FIG. 5 is an explanatory diagram of a circuit during cleaning of the connection mechanism.
FIG. 6 is an explanatory diagram of a circuit during electrostatic coating.
FIG. 7 is an explanatory diagram of a circuit when the air remaining in the connection portion of the first and second supply path portions is pushed out to the branch path.
FIG. 8 is an explanatory diagram of a circuit when the same color paint is filled.
FIG. 9 is an explanatory diagram of a circuit during cleaning of the connection mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electrostatic coating apparatus 12 ... Color change valve mechanism 14 ... Coating gun 16 ... Intermediate storage tank 18 ... Paint supply path 18a, 18b ... Supply path part 20 ... Dump path 20a, 20b ... Dump path part 22 ... Connection mechanism 24, 66, 112 ... Cleaning valve 28 ... Fixed block 30 ... Movable block 36, 38 ... Male valve element 40, 60 ... Through hole 42, 50, 52, 54, 62, 64, 72, 74, 76 ... Open / close valve 56 58 ... Female valve body 68, 70 ... Branch path 80 ... Cylinder 84 ... Cylinder chamber 106 ... Supply path 108 ... Trigger valve 110 ... Dump valve

Claims (2)

A paint supply path for supplying conductive paint to the coating gun, a first supply path section having a first on-off valve and communicating with a paint supply source, and a second supply path having a second on-off valve to which a high voltage is applied A process of electrically insulating and separating the part from the coating gun and deriving a conductive coating applied with a high voltage from the coating gun to perform electrostatic coating;
Connecting the first supply path and the second supply path after the electrostatic coating;
While the second on-off valve of the second supply path portion is closed, the third on-off valve provided on the upstream side of the second on-off valve and disposed on the branch path connected to the cleaning medium supply source is opened, When the first on-off valve of the first supply path section is opened in a state where the fourth on-off valve disposed on the branch path is closed, the conductive paint sent from the paint supply source is pressed. Pushing out the air remaining in the connecting portion of the first and second supply path portions between the third on-off valve and the fourth on-off valve;
Supplying the conductive paint to the coating gun side by closing the third on-off valve while the second on-off valve is opened after air remaining in the connection portion is removed;
An electrostatic coating method characterized by comprising: A connection mechanism for electrically insulating and separating a paint supply path for supplying conductive paint to the paint gun into a first supply path section communicating with a paint supply source and a second supply path section to which a high voltage is applied;
The connection mechanism includes a first connection part having a first on-off valve coupled to the first supply path part;
A second connecting part having a second on-off valve connected to the second supply path part and provided with a branch path connected to a cleaning medium supply source upstream of the second on-off valve;
With
The first and second connection portions are connected to the branch path, and the second on-off valve is closed, and the branch path is under the pressing action of the conductive paint sent from the first supply path portion. A third on-off valve that can be opened and a fourth on-off valve that can be closed when the second on-off valve is closed so as to push out the air remaining in the connecting portion of the first and second connecting portions to a part of the branch path. An electrostatic coating apparatus characterized by being connected.

Images