JP2514479B2 - Grounding method for 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 grounding method for an electrostatic coating apparatus in which a high voltage is directly applied to a conductive coating for electrostatic coating.

[0002]

2. Description of the Related Art Conventionally, as a technique for applying a high voltage directly to a conductive paint to electrostatically coat an object to be coated such as an automobile body, there is one disclosed in Japanese Patent Laid-Open No. 2-2885. Are known.

In this conventional technique, a conductive paint is once introduced from a paint supply source into an intermediate storage tank through an insulating pipe, and then this insulating pipe is washed and dried to be electrically insulated (voltage block). ) Is configured to prevent the current from leaking to the paint supply source side, the paint to which a high voltage is directly applied is supplied from the intermediate storage tank to the coating gun, and static electricity is applied to the object to be coated. Electric painting work is being performed.

[0004]

However, in this type of internal application type electrostatic coating apparatus, a considerable amount of electric charge remains in the coating material and the apparatus itself, especially in the intermediate storage tank. It has been pointed out that when the conductor is abnormally close to the conductor, sparks are generated due to the residual charges even if the application of the high voltage is stopped, which causes a coating failure or the like. That is, in the internal application type electrostatic coating device, it is particularly necessary to prevent leaks from various parts of the device as much as possible, and it takes a considerable time to release the residual charges.

The present invention solves this type of problem and allows the residual charge in the device to be discharged quickly and reliably, thereby preventing the occurrence of sparks even in the event of an abnormality and improving efficiency. An object of the present invention is to provide a grounding method for an electrostatic coating device capable of performing a typical electrostatic coating operation.

[0006]

In order to achieve the above-mentioned object, the present invention, when a high voltage is directly applied to a conductive paint for electrostatic coating, keeps a high potential by applying this high voltage. And a step of measuring the leakage current value at any part, a step of stopping the high voltage application when the measured leakage current value is equal to or higher than a reference value, and a step of stopping the high voltage application. In this state, a step of supplying a conductive fluid connected to the ground potential to a part formed of a conductive material among the parts held at the high potential.

[0007]

In the method of grounding the electrostatic coating apparatus according to the present invention, when it is detected that the leak current value from the portion held at the high potential is equal to or higher than the reference value during the electrostatic coating operation,
The application of the high voltage is stopped, and the conductive fluid at the ground potential is supplied to the conductive portion held at the high potential. Therefore, the conductive portion at the high potential is electrically connected to the ground potential via the conductive fluid, and the residual charge is quickly and surely discharged to the ground side.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A grounding method for an electrostatic coating apparatus according to the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates an electrostatic coating apparatus for carrying out the grounding method according to this embodiment.
This electrostatic coating device 10 includes a grounded color changing valve mechanism 12
An intermediate storage part 14 that temporarily stores the electrically conductive water-based paint supplied from the color change valve mechanism 12, a four-way switching valve 18 connected to the intermediate storage part 14 via a supply path 16, A coating gun 22 connected to the outlet side of the four-way switching valve 18 via a delivery path 20 is provided.

The color change valve mechanism 12 includes air (A) and water (W).
And a cleaning valve 24 for controlling the supply of cleaning liquid (S) and the like,
It is provided with a plurality of paint valves 26a to 26c capable of supplying water-based paints of different colors. This color change valve mechanism 1
The intermediate storage section 14 connected to the outlet side of 2 is separated from the storage tank 28 in which the water-based paint is temporarily stored by ensuring a predetermined distance from each other and arranged along the storage tank 28. 3-way switching valve 30 made of metal (having conductivity)
a, 30b and a block valve mechanism 34 provided with an insulating path 32 having a length capable of insulating a predetermined high voltage. On the inlet side of the three-way switching valve 30a, the color switching valve mechanism 1
2 and the first cleaning valve mechanism 36 that is grounded are connected to each other, and the first cleaning valve mechanism 36 includes at least the insulating path 3
A cleaning valve 38, which is a means for cleaning 2 with water (W) and a cleaning liquid (S), and an air supply valve 40, which is a means for drying the insulating path 32, are provided. A waste liquid tank 44 is connected to the outlet side of the three-way switching valve 30b via a discharge path 42.

The storage tank 28 is provided with a first cylinder chamber 48 for injecting paint, cleaning liquid, etc., which is divided via a piston 46.
And a second cylinder chamber 50 for air supply.
In the cylinder chamber 50, an air supply source 52 is provided with a flow rate adjusting valve 54,
It communicates via the on-off valve 56. This air supply source 52 is
It is connected to a paint flow rate controller 60 for adjusting the air pressure via the booster 58, and the flow rate controller 60 controls the discharge amount of the paint.

A four-way switching valve 18 is connected to the first cylinder chamber 48 of the storage tank 28 via a supply path 16, and the four-way switching valve 18 is connected to a flow rate controller 60 and a coating gun 22 via a delivery path 20. Connected to. A second cleaning valve mechanism 66 including a cleaning valve 62 and an air supply valve 64 is connected to the inlet side of the four-way switching valve 18, and the second cleaning valve mechanism 66 includes
It is connectable to the waste passage 70 via the delivery passage 20 and the discharge passage 68.

The coating gun 22 is provided with a dump valve 72, a trigger valve 74 and a high voltage applying means 75. The dump valve 72 is connected to a waste liquid tank 70 via a discharge path 76, and A washing valve 78 is provided on the way of the discharge path 76.
And a third cleaning valve mechanism 82 provided with an air supply valve 80 are connected.

In the electrostatic coating apparatus 10, for measuring the amount of current leaking from, for example, the three-way switching valve 30b, the four-way switching valve 18 and the dump valve 72 among the conductive parts that are kept at a high potential by applying a high voltage. The block valve mechanism 3
4 between the three-way switching valves 30a and 30b, and the discharge path 4
2, 68 and 76 include a first comparator 92 to a fourth comparator 9
8 are provided. The first comparator 92 includes a three-way switching valve 3
0a, while the second to fourth comparators 94 to 98 are provided with metal connectors 100, 102 and 104 provided along the discharge paths 42, 68 and 76, respectively.
Electrically connected to.

Next, the operation of the electrostatic coating apparatus 10 thus constructed will be described in connection with the grounding method according to this embodiment.

First, when the paint of a predetermined color derived from the paint valve 26a of the color changing valve mechanism 12 is supplied to the block valve mechanism 34 of the intermediate storage section 14, this paint is applied to the three-way switching valve 3
0a, the insulating path 32, and the three-way switching valve 30b to fill the first cylinder chamber 48 of the storage tank 28. This first
The paint with which the cylinder chamber 48 is filled passes through the supply path 16, the four-way switching valve 18 and the delivery path 20, and the coating gun 2
Fill up to 2. During this filling, the trigger valve 74 is closed, while the dump valve 72 is opened, and after the filling, the dump valve 72 is closed.

Then, the switching operation of the three-way switching valves 30a and 30b constituting the block valve mechanism 34 is performed, the first cleaning valve mechanism 36 communicates with one end side of the insulating path 32, and the other end of the insulating path 32. The side communicates with the waste liquid tank 44 via the discharge path 42. In this state, the first cleaning valve mechanism 3
The cleaning liquid under the driving action of the cleaning valve 38 constituting 6 cleans the three-way switching valve 30 a, the insulating path 32 and the three-way switching valve 30 b, and is discharged from the discharge path 42 to the waste liquid tank 44.

After the cleaning is completed, dry air is supplied from the air supply valve 40 constituting the first cleaning valve mechanism 36, and at least the inside of the insulating path 32 is dried by this dry air, so that the color change valve mechanism 12 and the storage tank 28 are connected. Are electrically isolated. Next, from the air supply source 52 to the flow rate adjustment valve 54
Driving air is supplied to the second cylinder chamber 50 of the storage tank 28 via the open / close valve 56, the piston 46 is displaced to the first cylinder chamber 48 side, and the paint is applied to the high voltage applying means 75.
Under the action of high voltage is directly applied to the trigger valve 74
Is supplied to the work (not shown) under the opening action.

As described above, when the high voltage is directly applied to the coating material under the action of the high voltage applying means 75, the portion kept at the high potential, specifically, the storage tank 28, the four-way switching valve 18 and the coating gun. The leakage current value at 22 etc. is determined by the first comparator 9
It is measured through the second to fourth comparators 98, respectively. Then, for example, when the leak current value measured by the first comparator 92 is equal to or greater than the reference value, the driving of the high voltage applying means 75 is stopped and the application of the high voltage to the paint is interrupted.

With the high voltage application stopped, the first
Water as a conductive fluid, cleaning liquid, etc. are supplied to the block valve mechanism 34 from the cleaning valve 38 which comprises the cleaning valve mechanism 36 (refer FIG. 2). Since this water and the like are discharged to the waste liquid tank 44 through the three-way switching valve 30a, the insulating path 32, the three-way switching valve 30b and the discharge path 42, the inside of the storage tank 28 and the supply path 16, which are held at a high potential, The paint in the delivery path 20 is electrically connected to the ground potential via the three-way switching valve 30b and water or the like. Therefore, the electric charge remaining in the storage tank 28 is quickly and surely discharged to the ground side through the water or the like, and the discharging work of the residual electric charge is performed in a considerably shorter time than the conventional electrostatic coating device. To be done. As a result, even if the coating gun 22 abnormally approaches a conductor such as a work immediately after the application of high voltage to the coating material is stopped, it is possible to effectively prevent the occurrence of sparks and the like, and cause coating failure. It is possible to obtain an effect that an efficient and highly accurate electrostatic coating work can be performed without any problem.

After the discharge of the residual charge is completed, the air supply valve 40 constituting the first cleaning valve mechanism 36 is driven to perform the drying operation of the insulating path 32. The four-way switching valve 18
The work of discharging the residual charge in the dump valve 72 and the dump valve 72 is performed in the same manner as the storage tank 28 described above, and a detailed description thereof will be omitted.

[0022]

According to the grounding method of the electrostatic coating apparatus of the present invention, the following effects can be obtained.

During the electrostatic coating operation, when it is detected that the leak current value from the portion kept at the high potential is equal to or higher than the reference value, the high voltage application is stopped and the high potential is maintained. Since the conductive fluid at the ground potential is supplied to the conductive portion, the conductive portion is electrically connected to the ground potential, and the residual charge can be quickly and surely discharged to the ground side. Therefore, even if a conductive member such as a workpiece approaches the coating gun or the like abnormally, the residual charge does not cause sparks or other inconveniences, and coating defects are avoided to perform highly accurate and efficient coating work. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an electrostatic coating apparatus for carrying out a grounding method according to this embodiment.

FIG. 2 is an explanatory diagram of the grounding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electrostatic coating device 12 ... Color change valve mechanism 14 ... Intermediate storage part 16 ... Supply path 18 ... Four-way switching valve 20 ... Delivery path 22 ... Coating gun 28 ... Storage tanks 30a, 30b ... Three-way switching valve 32 ... Insulation path 34 ... Block valve mechanism 36, 66, 82 ... Wash valve mechanism 92, 94, 96, 98 ... Comparator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ichiro Ishibashi 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (72) Inventor Hiroshi Arai 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Within the corporation

Claims (1)

(57) [Claims] 1. When a high voltage is directly applied to a conductive coating material for electrostatic coating, a process of measuring a leak current value at any part held at a high potential by the high voltage application, When the measured leakage current value is greater than or equal to a reference value, a process of stopping the high voltage application and a conductive material in a portion held at the high potential in the state where the high voltage application is stopped And a step of supplying a conductive fluid connected to a ground potential to the portion formed in (1).