Electrostatic coating apparatus and grounded state checking method

Patent metadata

Field	Value
Publication number	US-9415407-B2
Application number	US-201314432452-A
Country	US
Kind code	B2
Filing date	Oct 17, 2013
Priority date	Oct 17, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

An electrostatic coating apparatus includes: a spray gun configured to spray a coating material onto a coating object; a voltage application device configured to apply a high voltage to the spray gun; and a current measurement device configured to measure electric current flowing through the spray gun. When the spray gun, which is in a state of not spraying the coating material onto the coating object and is under application of the high voltage from the voltage application device, is located at a distance from the coating object, the electric current flowing through the spray gun is measured by the current measurement device. A grounded state of the coating object is checked, based on the measured electric current. This shortens the time required for checking the grounded state, while allowing for downsizing and simplified configuration of production equipment and reduction of equipment cost.

First claim

The invention claimed is:

1. An electrostatic coating apparatus, comprising:
a spray gun configured to spray a coating material onto a coating object;
a voltage application device configured to apply a high voltage to the spray gun; and
a current measurement device configured to measure electric current flowing through the spray gun, wherein
the electrostatic coating apparatus is configured to locate the spray gun, which is in a state of not spraying the coating material onto the coating object and is under application of the high voltage from the voltage application device, at a distance from the coating object, so as to measure the electric current flowing through the spray gun by the current measurement device,
the electrostatic coating apparatus being configured to check a grounded state of the coating object, based on the electric current measured by the current measurement device.

2. The electrostatic coating apparatus according to claim 1 ,
wherein the electrostatic coating apparatus is configured to locate the spray gun which is under application of the high voltage from the voltage application device, in at least three or more different positions at a fixed distance from the coating object located at its normal position, so as to measure the electric current flowing through the spray gun by the current measurement device at each of the three or more different positions,
the electrostatic coating apparatus being configured to check the grounded state of the coating object, based on a plurality of the electric currents measured by the current measurement device.

3. The electrostatic coating apparatus according to claim 1 , further comprising:
a surface potential measurement device electrically connected with the spray gun and configured to measure a surface potential on the coating object, wherein
the electrostatic coating apparatus is configured to locate the spray gun, which is in the state of not spraying the coating material onto the coating object and is under application of the high voltage from the voltage application device, at a distance from the coating object, so as to charge the coating object, while being configured to locate the spray gun, which is under no application of the high voltage from the voltage application device, at a distance from the coating object, so as to measure the surface potential on the coating object by the surface potential measurement device,
the electrostatic coating apparatus being configured to check the grounded state of the coating object, based on the electric current measured by the current measurement device and the surface potential measured by the surface potential measurement device.

4. The electrostatic coating apparatus according to claim 3 ,
wherein when the grounded state of the coating object is abnormal, the electrostatic coating apparatus is configured to identify a cause of the abnormal grounded state, based on the electric current measured by the current measurement device and the surface potential measured by the surface potential measurement device.

5. The electrostatic coating apparatus according to claim 4 ,
wherein the electrostatic coating apparatus is configured to identify the cause of the abnormal grounded state by comparison between a value Y (kV) and a calculated value by substituting a value X (kV) into −3 (μA/kV)×X+20 (μA),
where the value X is calculated by subtracting the surface potential on the coating object in a normal grounded state measured by the surface potential measurement device from the surface potential on the coating object as a test object measured by the surface potential measurement device, and
the value Y is calculated by subtracting the electric current on the coating object as the test object measured by the current measurement device from the electric current on the coating object in the normal grounded state measured by the current measurement device.

6. The electrostatic coating apparatus according to claim 3 ,
wherein the electrostatic coating apparatus is configured to locate the spray gun, which is in the state of not spraying the coating material onto the coating object and is under application of the high voltage from the voltage application device, at a distance from the coating object, so as to measure the electric current flowing through the spray gun by the current measurement device and charge the coating object by the spray gun.

7. The electrostatic coating apparatus according to claim 3 ,
wherein the spray gun includes a first spray gun and a second spray gun, wherein
the electrostatic coating apparatus is configured to locate the first spray gun, which is under application of the high voltage from the voltage application device, at a distance from the coating object, so as to charge the coating object, while being configured to locate the second spray gun, which is under no application of the high voltage from the voltage application device, at a distance from the coating object, so as to measure the surface potential on the coating object by the surface potential measurement device.

8. The electrostatic coating apparatus according to claim 3 ,
wherein a distance between the spray gun and the coating object during measurement of the surface potential on the coating object by the surface potential measurement device is made smaller than a distance between the spray gun and the coating object during coating of the coating object by the spray gun.

9. The electrostatic coating apparatus according to claim 1 ,
wherein a distance between the spray gun and the coating object during measurement of the electric current flowing through the spray gun by the current measurement device is made smaller than a distance between the spray gun and the coating object during coating of the coating object by the spray gun.

10. The electrostatic coating apparatus according to claim 1 ,
wherein a distance between the spray gun and the coating object is not less than 40 mm and not greater than 100 mm during measurement of the electric current flowing through the spray gun by the current measurement device.

11. The electrostatic coating apparatus according to claim 1 ,
wherein a distance between the spray gun and the coating object is not less than 60 mm and not greater than 80 mm during measurement of the electric current flowing through the spray gun by the current measurement device.

12. A grounded state checking method of checking a grounded state of a coating object in an electrostatic coating apparatus comprising a spray gun configured to spray a coating material onto a coating object and a voltage application device configured to apply a voltage to the spray gun,
the grounded state checking method comprising:
measuring an electric current flowing through the spray gun when the spray gun, which is under application of a high voltage by the voltage application device, is located at a distance from the coating object; and
checking a grounded state of the coating object, based on the measured electric current.

13. The grounded state checking method according to claim 12 ,
wherein the measuring the electric current flowing through the spray gun is performed when the spray gun, which is in a state of not spraying the coating material onto the coating object, is located in at least three different positions at a fixed distance from the coating object located in its normal position.

14. The grounded state checking method according to claim 12 , further comprising:
charging the coating object and measuring a surface potential on the coating object when the spray gun, which is under application of a voltage by the vol

Assignees

• Trinity Ind Corp
• Toyota Jidosha Kabushika Kaisha
• Toyota Motor Co Ltd

Inventors

• Umeki Masayuki
• Kawamoto Akihiro
• Fujiwara Shigeki
• Yamasaki Isamu
• Asada Yasunori
• Nagai Kimiyoshi

Classifications

• G01R31/50

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title

• B05B5/04

  characterised by having rotary outlet or deflecting elements {, i.e. spraying being also effected by centrifugal forces} · CPC title

• B05B12/084

  responsive to condition of liquid or other fluent material already sprayed on the target, e.g. coating thickness, weight or pattern · CPC title

• B05B13/0431

  with spray heads moved by robots or articulated arms, e.g. for applying liquid or other fluent material to three-dimensional [3D] surfaces · CPC title

• B05B5/0407 Primary

  with a spraying edge, e.g. like a cup or a bell · CPC title