JP4603768B2 - Electrostatic coating method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, after the paint is once supplied from the supply source to the intermediate storage mechanism, the paint is supplied to the coating gun in a state where the supply source and the intermediate storage mechanism are electrically cut off. about the painting how.
[0002]
[Prior art]
For example, a voltage block method is known as a method of applying a high voltage to a conductive paint to apply electrostatic coating to an object to be coated such as an automobile body. In this method, after the conductive paint is once introduced into an intermediate storage tank (intermediate storage mechanism) that is insulated from the ground potential, the supply path that connects the intermediate storage tank and the paint supply source is washed and Dry to form a voltage block. In this state, an electrostatic coating operation is performed on an object to be coated by supplying a conductive paint to which a high voltage is applied from the intermediate storage tank to the coating gun.
[0003]
For example, Patent Document 1 is known as an electrostatic coating apparatus used for this type of coating. In Patent Document 1, as shown in FIG. 7, a pump 1 is provided as an intermediate storage mechanism, and a paint inflow port 1 a of the pump 1 is filled with a conductive paint from a paint supply path 2. On the other hand, the conductive paint is pressure-fed from the paint discharge port 1b of the pump 1 to the coating machine 3 by a predetermined amount.
[0004]
The pump 1 includes a piston 4, and the piston 4 can be advanced and retracted by high-pressure air supplied from an air supply source 5 through a pressure adjustment valve 6. The moving speed of the piston rod 4a connected to the piston 4 is detected by a non-contact sensor 7, and the flow rate of the conductive paint supplied to the coating machine 3 is measured based on the moving speed of the piston rod 4a. Is done.
[0005]
Then, the measured flow rate of the conductive paint and the flow rate set in advance according to the paint discharge amount of the coating machine 3 are compared, and the pressure of the high-pressure air supplied to the pump 1 is determined according to the difference value. It is variably adjusted via the pressure adjustment valve 6. Thus, the pump 1 can be miniaturized and the quantitative property of the conductive paint stored in the pump 1 can be ensured.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-60452 (FIG. 1)
[0007]
[Problems to be solved by the invention]
By the way, in said pump 1, in order to supply the coating material 3 with the electroconductive coating material supplied to this pump 1, and to perform coating, the pump 1 is filled with the coating material. There is a risk of air entering when filling the paint. At that time, the air mixed in the paint and introduced into the pump 1 easily moves to the upper side in the pump 1.
[0008]
However, in the pump 1, the paint discharge port 1b is provided above the paint inflow port 1a. For this reason, as shown in FIG. 8, when the piston 4 moves forward (in the direction of the arrow X) and the paint in the pump 1 is supplied to the coating machine 3, the air staying on the upper side in the pump 1. However, it will be sent to the said coating machine 3 from the coating material discharge outlet 1b. As a result, there is a problem that air is mixed in the paint discharged from the coating machine 3 to the object to be coated, an appropriate coating pattern cannot be formed, and high-precision electrostatic coating work cannot be performed. ing.
[0009]
In addition, when the color is changed in order to newly use a paint of a different color, an operation for cleaning the inside of the pump 1 is performed. At that time, the cleaning liquid supplied into the pump 1 from the paint inlet 1a is discharged from the paint discharge port 1b. However, since the paint discharge port 1b is provided above the paint inlet 1a, the cleaning liquid tends to remain in the pump 1, and the new paint supplied to the pump 1 after cleaning and the cleaning liquid are mixed. . For this reason, the paint to be discarded is generated, which is not economical, and electrostatic coating may be performed by the paint mixed with the cleaning liquid.
[0010]
The present invention solves this type of problem, and with a simple process and configuration, air and cleaning liquid are reliably prevented from being mixed in the paint supplied from the intermediate storage mechanism to the paint gun, and high quality static aims to electrostatic coating operations is to provide an electrostatic painting how possible execution.
[0011]
[Means for Solving the Problems]
In the electrostatic coating method according to the present invention, after the paint is supplied from the paint supply source into the intermediate storage mechanism through the injection hole of the intermediate storage mechanism mounted on the robot arm of the electrostatic coating apparatus , The inside of the electrically insulating conduit interposed between the supply source and the intermediate storage mechanism is cleaned, and the paint in the intermediate storage mechanism is supplied to the coating gun through the discharge hole, and electrostatic coating is performed. Has been done.
[0012]
Here, at least when the color change cleaning is performed (color change cleaning process) or when the conductive paint is supplied to the coating gun (painting process), the electrostatic storage is performed while maintaining the intermediate storage mechanism substantially horizontal by the robot arm. The coating is performed and the injection hole is disposed above the discharge hole. In the color change cleaning process, since the cleaning liquid is supplied into the intermediate storage mechanism, this cleaning liquid tends to remain in the lower part of the intermediate storage mechanism. At this time, the discharge hole portion of the intermediate storage mechanism is disposed below the injection hole portion, and the cleaning liquid remaining in the lower portion of the intermediate storage mechanism is reliably discharged through the discharge hole portion. As a result, the new coating material supplied into the intermediate storage mechanism is not mixed with the cleaning liquid, the discarded coating material is effectively reduced, and a high-quality electrostatic coating operation is easily performed.
[0013]
On the other hand, when the paint is supplied from the supply source to the intermediate storage mechanism through the injection hole, if air enters the intermediate storage mechanism, the air tends to stay in the upper part of the intermediate storage mechanism. Therefore, in the painting process, the discharge hole portion of the intermediate storage mechanism is disposed below the injection hole portion.
[0014]
For this reason, when the paint in the intermediate storage mechanism is supplied from the discharge hole portion to the coating gun, the air staying in the upper portion in the intermediate storage mechanism is not introduced into the coating gun from the discharge hole portion. . This reliably prevents air from being mixed in the paint supplied from the intermediate storage mechanism to the coating gun with a simple process and configuration, and enables high-quality electrostatic coating work to be easily performed. In the coating step, the electrostatic coating may be performed on the automobile body.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration explanatory diagram of an electrostatic coating apparatus 10 for carrying out the electrostatic coating method according to the present invention.
[0017]
The electrostatic coating apparatus 10 includes a color change valve mechanism 12 that is grounded. The color change valve mechanism 12 controls the supply of drying air (A), water (W), cleaning liquid (S), and the like. One cleaning valve 14 and a plurality of paint valves 16a, 16b and 16c capable of supplying conductive paints of different colors are provided. A block valve mechanism 20 is connected to the color change valve mechanism 12 via a supply path 18a, and a first discharge path 23 is connected to the supply path 18a via a first dump valve 21.
[0018]
The block valve mechanism 20 has a resin-made electrically insulating conduit (supply passage) 18b, and switching valves 22a and 22b are connected to both ends of the electrically insulating conduit 18b. The switching valve 22a on the inlet side switches between the color change valve mechanism 12 and the second cleaning valve 24 that controls the supply of air (A), water (W), cleaning liquid (S), etc., and the switching valve on the outlet side. The intermediate storage tank (intermediate storage mechanism) 26 is switched through the second discharge path 25 and the supply path 18c by 22b.
[0019]
The intermediate storage tank 26 includes a cylinder container 26a made of an insulating resin, and a cylinder chamber 30 for injecting conductive paint and cleaning liquid is formed in the cylinder container 26a via a piston 28. The cylinder chamber 30 communicates with an injection hole 32 and a discharge hole 34, and the injection hole 32 is disposed above the discharge hole 34. A servo motor 36 is connected to a rod 28a made of an insulating resin extending from the piston 28 via a ball screw means 37, and the piston 28 can advance and retreat in the direction of arrow A.
[0020]
A coating gun 40 is connected to the cylinder chamber 30 of the intermediate storage tank 26 via a delivery path 38. The coating gun 40 includes a second dump valve 42 and a trigger valve 44 and is connected to a high voltage applying unit (not shown). The second dump valve 42 is connected to a third discharge path 46 for discharging the drainage liquid containing the conductive paint and the cleaning liquid generated during cleaning to the outside of the delivery path 38.
[0021]
A third cleaning valve 48 that controls the supply of air (A), water (W), cleaning liquid (S), and the like is connected to the third discharge path 46.
[0022]
As shown in FIGS. 2 and 3, the mounting plate 62 is fixed to the movable portion of the electrostatic coating apparatus 10, for example, the robot arm 60, and the insulating cradle 64 is fixed to the mounting plate 62. An insulating support base 66 is screwed to the receiving base 64, for example, and the cylinder container 26a constituting the intermediate storage tank 26 is supported in a horizontal posture via the support base 66.
[0023]
An insulating plate 68 is fixed on the support base 66, and switching valves 22 a and 22 b are mounted on the insulating plate 68 on the side opposite to the intermediate storage tank 26. The insulating cover 70 is detachably screwed to the cradle 64 so as to cover the intermediate storage tank 26.
[0024]
On the mounting plate 62, the color change valve mechanism 12, the second cleaning valve 24, and the servo motor 36 are mounted. A ball screw 72 constituting a ball screw means 37 is coaxially connected to the rotation shaft 36a of the servo motor 36. The ball screw 72 extends in the direction of arrow A and is rotatably supported by the frame member 74. Is done.
[0025]
The frame member 74 is provided with linear guides 76 located on both sides of the ball screw 72, and a movable table 78 is disposed on the linear guide 76 so as to freely advance and retract. The movable table 78 includes a nut portion into which the ball screw 72 is screwed. The rear end of the rod 28a is fixed to the movable table 78.
[0026]
The robot arm 60 is maintained in a substantially horizontal posture when performing a painting operation, and in this substantially horizontal posture, the discharge hole portion 34 of the intermediate storage tank 26 is always disposed below the injection hole portion 32. Yes.
[0027]
Next, operation | movement of the electrostatic coating apparatus 10 comprised in this way is demonstrated in relation to the electrostatic coating method which concerns on this invention.
[0028]
First, the supply path 18a, the electrically insulating pipe line 18b, and the supply path 18c are connected via the switching valves 22a and 22b of the block valve mechanism 20. Then, for example, the paint valve 16a of the color change valve mechanism 12 is opened, and the servo motor 36 of the intermediate storage tank 26 is driven.
[0029]
For this reason, as shown in FIG. 1, the conductive paint of a predetermined color is pumped from the paint valve 16a. The conductive paint is filled into the cylinder chamber 30 of the cylinder container 26a through the supply path 18a, the electrically insulating pipe line 18b, and the supply path 18c, and is further supplied to the coating gun 40 through the delivery path 38.
[0030]
When the filling of the conductive paint into the cylinder chamber 30 of the cylinder container 26a is completed, the block valve mechanism 20 is cleaned. Specifically, as shown in FIG. 4, the switching valves 22a and 22b of the block valve mechanism 20 are switched, and the second cleaning valve 24 is connected to the second discharge path 25 via the electrically insulating conduit 18b. The
[0031]
Accordingly, when the cleaning liquid (water or thinner) is supplied from the second cleaning valve 24, the inside of the electrically insulating conduit 18 b is cleaned, and the waste liquid is discharged to the second discharge path 25. Further, air is supplied from the second cleaning valve 24 to dry the inside of the electrically insulating conduit 18b, and electrical insulation is made between the switching valves 22a and 22b.
[0032]
Next, as shown in FIG. 5, the trigger valve 44 is opened, and the piston 28 moves in the direction of the arrow A <b> 2 under the drive action of the servo motor 36. Paint is pumped. For this reason, the conductive paint is discharged from the coating gun 40 via the trigger valve 44, and a high voltage is applied to the conductive paint, whereby electrostatic painting is performed on the object to be coated.
[0033]
By the way, as shown in FIG. 1, when conductive paint is supplied from the paint valve 16a through the injection hole 32 to the cylinder chamber 30 of the cylinder container 26a, if air enters the cylinder chamber 30, this air Tends to stay in the upper part of the cylinder chamber 30.
[0034]
In this case, in the present embodiment, the discharge hole portion 34 of the cylinder container 26 a is disposed below the injection hole portion 32. For this reason, as shown in FIG. 6, when the piston 28 moves in the direction of the arrow A2 and the conductive paint in the cylinder chamber 30 is supplied to the coating gun 40 from the discharge hole portion 34, the cylinder chamber 30 enters the cylinder chamber 30. The staying air is not introduced into the coating gun 40 from the discharge hole 34.
[0035]
Accordingly, it is possible to reliably prevent air from being mixed into the paint supplied from the intermediate storage tank 26 to the coating gun 40 with a simple process and configuration, and to perform high-quality electrostatic painting work easily. An effect is obtained.
[0036]
Further, in the present embodiment, as shown in FIG. 2, the intermediate storage tank 26 is attached to the robot arm 60, and when the robot arm 60 is in a substantially horizontal posture, the injection hole portion 32 is the discharge hole portion 34. It is arranged above. Therefore, when the painting posture of the robot arm 60 is maintained in a substantially horizontal posture, the discharge hole portion 34 of the intermediate storage tank 26 is always disposed below the injection hole portion 32. For this reason, it can prevent as much as possible that the conductive paint in which air was mixed is supplied to the coating gun 40.
[0037]
When a different color conductive paint is used after the electrostatic coating is completed, the application of the high voltage to the coating gun 40 is canceled and the switching valves 22a and 22b of the block valve mechanism 20 are switched. Switch. Accordingly, the cleaning liquid is injected into the cylinder chamber 30 of the cylinder container 26a under the driving action of the first cleaning valve 14. The cleaning liquid is discharged from the third discharge path 46 under the action of the second dump valve 42 after cleaning the cylinder chamber 30 and the delivery path 38. Then, different colors of conductive paint are supplied to the cylinder chamber 30 of the cylinder container 26a through, for example, the paint valve 16b of the color change valve mechanism 12, and the different colors are applied by the same method as described above. .
[0038]
In this case, when the cylinder chamber 30 of the cylinder container 26 a is cleaned, the cleaning liquid injected into the cylinder chamber 30 is surely discharged from the discharge hole 34 provided below the injection hole 32. For this reason, when conductive paint of a different color is supplied to the cylinder chamber 30, it is not mixed with the cleaning liquid remaining in the cylinder chamber 30. Accordingly, there is an advantage that the color change cleaning operation of the conductive paint can be performed efficiently and reliably with a simple configuration, and the efficiency of the entire color change coating operation can be easily performed.
[0039]
In the present embodiment, the robot arm 60 is used as the movable part of the electrostatic coating apparatus 10. However, the present invention is not limited to this, and for example, an intermediate on a transport table that is movable in three orthogonal axes. A storage tank 26 may be attached.
[0040]
【The invention's effect】
The electrostatic coating how according to the present invention, at least color change washing step or coating step, discharge hole portion is arranged below the injection hole. For this reason, in the color change cleaning process, the cleaning liquid remaining in the lower portion of the intermediate storage mechanism is reliably discharged through the discharge hole. As a result, the new coating material supplied into the intermediate storage mechanism is not mixed with the cleaning liquid, the discarded coating material is effectively reduced, and a high-quality electrostatic coating operation is easily performed.
[0041]
On the other hand, in the painting process, when the paint in the intermediate storage mechanism is supplied from the discharge hole portion to the coating gun, air staying in the upper portion in the intermediate storage mechanism may be introduced into the coating gun from the discharge hole portion. Absent. Therefore, it is possible to reliably prevent air from being mixed in the paint supplied from the intermediate storage mechanism to the coating gun with a simple process and configuration, and to easily perform high-quality electrostatic painting work.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a schematic configuration of an electrostatic coating apparatus for carrying out an electrostatic coating method according to the present invention.
FIG. 2 is a side view showing a state where an intermediate storage tank is attached to the robot arm of the electrostatic coating apparatus.
FIG. 3 is a plan view of the mounted state shown in FIG.
FIG. 4 is an operation diagram for explaining a cleaning operation of a block valve mechanism constituting the electrostatic coating apparatus.
FIG. 5 is an operation diagram for explaining a painting operation by the electrostatic coating apparatus.
FIG. 6 is an operation explanatory diagram when air is present in the intermediate storage tank.
7 is an explanatory diagram of a schematic configuration of an electrostatic coating apparatus according to Patent Document 1. FIG.
8 is an operation explanatory diagram of a pump constituting the electrostatic coating apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electrostatic coating apparatus 12 ... Color change valve mechanism 14, 24 ... Washing valve 16a-16c ... Paint valve 18a, 18c ... Supply path 18b ... Electrical insulation pipe line 20 ... Block valve mechanism 22a, 22b ... Switching valve 26 ... Intermediate storage tank 26a ... Cylinder container 28 ... Piston 30 ... Cylinder chamber 32 ... Injection hole 34 ... Discharge hole 36 ... Servo motor 40 ... Paint gun 60 ... Robot arm

Claims (3)

A paint supply step of supplying the paint into the intermediate storage mechanism from a paint supply source via an injection hole of the intermediate storage mechanism mounted on the robot arm of the electrostatic coating apparatus ;
A cleaning step of cleaning the inside of the electrically insulating conduit interposed between the supply source and the intermediate storage mechanism after the coating material is supplied into the intermediate storage mechanism;
The paint in the intermediate storage mechanism is applied through the discharge hole of the intermediate storage mechanism in a state where the supply source and the intermediate storage mechanism are electrically cut off by cleaning the inside of the electrically insulating conduit The painting process to supply to the gun and perform electrostatic painting,
And having
At least in the painting step, the electrostatic painting is performed while maintaining the intermediate storage mechanism substantially horizontal by the robot arm so as to prevent air from being mixed into the paint supplied from the intermediate storage mechanism to the coating gun. The electrostatic coating method is characterized in that the injection hole portion is disposed above the discharge hole portion. The electrostatic coating method according to claim 1 ,
Prior SL painting process, electrostatic coating method and performing the electrostatic coating against an automobile body. The electrostatic coating method according to claim 1 or 2, further comprising a color change cleaning step of cleaning the inside of the intermediate storage mechanism from the supply source when a paint having a color different from that of the paint is used.
In the color change cleaning step, the injection hole is disposed above the discharge hole so as to discharge the cleaning liquid injected into the intermediate storage mechanism from the intermediate storage mechanism. Electrostatic coating method.

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