JPS5953107B2 - Paint supply control method in electrostatic coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paint supply control method in an electrostatic coating apparatus.

Electrostatic painting is, as is well known, a grounded object to be coated as an anode, a high negative voltage applied to the paint spraying means, which serves as a cathode, and an electric field is created between these two electrodes to produce negatively charged paint. This is a method in which particles are made to fly in the direction of an electric field and are attracted to the object to be coated, which is the opposite electrode.

The paint spraying means is (a) a so-called process disk type, in which a disk to which a high voltage is applied is rotated, and the paint supplied from the center of the disk is atomized at the edge of the disk; (b) a high voltage is applied; The gun type is known to have a needle-shaped electrode that forms an ionization region in its vicinity, and paint particles that have been atomized by air or other mechanical means pass through this ionization region to become negatively charged. It is being

These means having a function of spraying a solvent paint or discharging a powder paint and to which a high voltage is applied are collectively referred to as a coating gun. Conventionally, a so-called reciprocator has been known that mechanically reciprocates this coating gun to coat an object to be coated.

As shown in FIG. 1, this reciprocator has a coating gun 3 attached to a carriage 2 that reciprocates along a guide rail 1. Reference numeral 4 indicates an object to be coated, for example, an automobile body.

The coating gun 3 is a gun-type coating gun, and a needle-like electrode to which a negative high voltage is applied is installed at the tip of the gun.

An electric field E is formed between this needle-like electrode and the vehicle body 4 serving as the object to be coated, and a current is generated in a high voltage generator (not shown), the coating gun 3, and the vehicle body 4 through this electric field E. Then, it passes through the ionization region near the needle electrode,
The negatively charged paint particles fly toward the vehicle body 4 along the electric field E.

L indicates the spraying distance. 5 is a trolley, and 6 is a floor Ron pair.

The floorron pair 6 is adapted to be driven by pulling the trolley 5. A pair of limit switches 7 and 8 (however, only one side is shown) are provided on the left and right sides integrally with the guide rail, and are activated by the dogs 2a and 2b of the carriage 2. That is, when the limit switch 7 is activated, a switching valve in the paint supply circuit is turned on and off to control the supply and stop of paint.

When the limit switch 8 is activated, the carriage 2 is instructed to switch between forward movement and backward movement, or to standby.
However, in such electrostatic painting equipment, the paint supply is controlled by a limit switch, so each time the vehicle body is changed, the Limit I switch must be moved, or the limit switch must be set to the maximum width. In the former case, it was difficult to move the limit switch, and in the latter case, there was a problem that paint was often sprayed.

This invention has been made in view of the above points, and the current flowing through the high voltage circuit including the high voltage generator for applying the high voltage and the electric field changes the distance between the painting gun and the object to be coated. Focusing on the point that changes functionally with respect to This method attempts to solve the conventional problems by opening the paint supply valve and spraying paint only in the range where the standard value is exceeded.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals.

10 is a paint supply means including a paint tank and a pump.

The paint supply means 10 and the paint gun 3 are...
4, and there is a solenoid valve 1 in the middle of the hose 14.
1 is inserted. Paint supply means 10, solenoid valve 11.
The hose 14 constitutes a paint supply path]5. 12 is a high voltage generator.

A high voltage circuit 16 is formed including the high voltage generator 12, the needle electrode of the paint gun 3, the electric field E, and the vehicle body 4? and current 1 flows. The relationship between current 1 and spray distance L is as shown in Fig. 3, and the reference spray distance Lp (for example, 30 cIn)
The current corresponding to is the reference current 1, (for example, 200 μA).

．．
[13 indicates a paint supply control section, which works as follows. The spraying distance LH corresponding to the set current value h lower than the reference current value 1p is greater than the standard spraying distance Lp) and the current I during painting work, and only when I<h. , outputs a signal k to the solenoid valve 11. The solenoid valve 11 is switched from the state shown in the figure to cut off the hose 14 only while the signal k is being input. Therefore, when the paint gun 3, which is moving at a constant height relative to the car body 4, is away from the car body 4, paint is no longer supplied to the paint gun 3, and the paint gun 3 approaches the car body 4. Then, the spraying distance L is the above-mentioned L.

If the current becomes smaller, the current 1>h, so the paint supply control section 13 no longer outputs the signal k. Therefore, the electromagnetic valve 11 is switched as shown in the figure, and paint is supplied to the coating gun 3. As described above, the present invention detects the current flowing through the high voltage circuit of an electrostatic coating device, compares this detected value with a preset reference value, and supplies paint only when the detected value exceeds the reference value. Since the paint is sprayed by opening the valve in the flow path, the width of the coating can be automatically changed even if the size of the object to be coated changes, which has the effect of extremely reducing waste of paint. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining the paint supply method in a conventional electrostatic coating device, FIG. 2 is a configuration diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between spraying distance and current. It is a line diagram showing a relationship. 1...Guide rail, 2...Carriage, 3...Painting gun, 4...Car body (subject to be painted), 10... Paint supply means, 11...
...Solenoid valve, 12...High voltage generator, 13...
... Paint supply control section, 15 ... Paint supply path, 16 ... High voltage circuit.

Claims (1)

[Claims] 1 Detect the current flowing in the high voltage circuit of the electrostatic coating device,
The electrostatic coating is characterized in that this detected value is compared with a preset reference value, and the valve of the paint supply path is opened to spray paint only when the detected value exceeds the reference value. A method for controlling the supply of paint in a device.