JPS6053667B2 - Abnormality detection device for paint supply system of electrostatic coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abnormality detection device for a paint supply system of an electrostatic coating device, and is an abnormality detecting device for detecting an abnormality such as discharge occurring in the paint supply system by a change in current passing through a high resistance. This invention relates to a detection device.

Generally, when performing electrostatic painting using low-resistance paints such as water-based or conductive paints, the paint supply system must be placed on an insulating stand and insulated; If the discharge energy increases, there is a risk of fire accidents due to the use of highly flammable solvents.

The present invention detects abnormalities such as electrical discharge that occur in the paint supply system and takes safety measures.The present invention includes a system that detects abnormalities by detecting the value of current flowing through high resistances provided in the legs of an insulating table. This is what we provide.

An abnormality in the paint supply system may occur if the electrostatic gun itself discharges in some way, if the paint hose is damaged, or if the paint tank (paint pressure tank) or insulating stand discharges. In that case, the current flowing through the high resistance will be less than the specified current value. Hereinafter, the present invention will be described with reference to an illustrated embodiment.

1 is a high voltage generator; an electrostatic gun 3 is connected to the tip of a high voltage cable 2 connected to the generator 1;
The base end of the paint hose 4 connected to the paint tank 5 is connected to the paint tank 5.

The paint tank 5 is placed on an insulating stand 6, and a leg 6a of the insulating stand 6 is provided with a high-resistance grounding part 7 having a high resistance 7 arranged thereon.
' is provided. Reference numeral 8 denotes a current detection control circuit, which is connected to the high resistance ground section 7'.

In the figure, reference numeral 9 denotes a solenoid for operating the discharge device which receives an abnormality detection signal from the current detection control circuit 8. The solenoid 9 is configured to control the operating air of the discharge device 10, the paint tank 5, and the electrostatic gun 3. In the above configuration, a high voltage is applied to the electrostatic gun from the high voltage generator 1 through the high voltage cable 2, and paint is supplied from the paint tank 5 to the electrostatic gun via the paint hose 4 to perform electrostatic painting. It is done.

Here, when painting is being performed normally, voltage is applied to the paint tank 5 via the paint, and a certain amount of voltage is leaked to the ground side through the high resistance 7 of the leg 6a of the insulating stand 6. . For example, the earth current under normal conditions is 5 to 7 μA (
It is grounded with a high resistance 7 while maintaining a constant voltage necessary for electrostatic painting. and,
When spraying is stopped, the system gradually discharges electricity through the resistor after a certain period of time and no voltage is applied.
The present invention guides the ground current flowing through the high resistance 7 to the current detection control circuit 8 and detects the current value. Therefore,
For example, if a grounded object approaches or discharges to the tip of the insulating stand 6 or the electrostatic gun 3, or if a paint hose is damaged, the current will flow to the abnormal side, so the current flowing to the high resistance 7 will be normal. The current decreases from 5 to 7 μA to 5 to 0 μA.

In this state, if the current value is below the set level, it can be determined that there is an abnormality. That is, the current setting level of the object to be coated in the current detection control circuit 8 is set to, for example, 5 μA, and this value is set as a danger line, and if it is below this level, it can be determined that an abnormality has occurred.

For example, in the ground current graph in Figure 2, when the grounding object is brought close to the insulating stand, 300T! $Ll2O
``If we create an unusual condition with a 100 order, the current flowing through the resistor will drop significantly. Of course, if the approach distance is 0wt, the current flowing will inevitably be 0μ.
It becomes A. In addition to the above-mentioned abnormal conditions, this current detection also occurs when the power supply of the electrostatic gun 3 is activated but normal current does not flow for some reason (for example, gun failure, lack of paint, etc.). Since the circuit 8 is activated, it becomes possible to take necessary measures.

Mutual control between the current detection control circuit 8 and the high voltage generator 1 is necessary when timing charging and detection, and when cutting off the power to the high voltage generator 1 based on the detection result. Generally, electrostatic painting is performed while the electrostatic gun 3 is turned on and off, so when detecting an abnormality on the insulating stand, it is necessary to
With FF, current response through high resistance and detector responsivity become a problem. In order to prevent this delay, the current detection control circuit receives the ON signal from the high voltage generator 1, and after delaying the operation for a certain period of time using a timer or the like, a detection judgment is performed.
If the detection result is NG, shut off the high voltage generator power supply, remove the defective part, and reset the electrostatic gun 3.
The system can be re-charged. As described above, the abnormality detection device of the present invention is a system that guides the ground current flowing through the high resistance attached to the leg of the insulating stand of the paint tank to the current detection control circuit, and determines abnormality by observing changes in the current value. This system reliably detects abnormalities such as electrical discharge, receives abnormal signals from the current control circuit, and, for example, eliminates static electricity from the charging system (discharge from the legs of the insulated table), removes pressurized pressure from the paint tank (stops the supply of paint, etc.) ), various controls such as stopping the gun blowing (operating) air, stopping charging of the high voltage generator, etc. are possible.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a system diagram showing the main parts, and FIG. 2 is a graph showing the relationship between ground approach distance and current value. 1... High voltage generator, 3... Electrostatic gun, 4... Paint hose, 5... Paint tank,
6...Insulation stand, 7...High resistance, 7''
...High resistance ground section, 8...Current detection control circuit.

Claims (1)

[Claims] 1. In an electrostatic coating device in which the paint supply system is placed on an insulating stand and a high resistance is arranged between the insulating stand and the ground, a current detection control circuit is installed to detect changes in the current flowing from the insulating stand through the high resistance, and the current value is A paint supply system abnormality detection device for electrostatic coating equipment that detects abnormalities based on changes.