JPS5817865A - Coatng material feed controlling method of electrostatic coating device - Google Patents

Abstract

PURPOSE:To reduce waste of a coating material, by detecting a current of an electrostatic coating device, comparing it with a reference value, spraying a coating material only within a range exceeding the reference value, and automatically changing an applied surface in accordance with a variation of size of an object to be coated. CONSTITUTION:A set current IH being lower than a reference current value is compared with a current I in case of a coating work, and only in case of I<IH, a signal K is outputted to a solenoid valve 11. The solenoid valve 11 cuts off a hose 14 only while the signal K is inputted. Accordingly, when a coating gun 3 moving at constant height against a car body 4 is separated from the car body 4, a coating material is not supplied to the coating gun 3. Also, when the coating gun 3 approaches the car body 4, and the spraying distance becomes smaller than a spraying distance corresponding to the set voltage IH, the current I becomes <IH, therefore, a coating material feed control part 13 does not output the signal K. As a result, the solenoid valve 11 is switched, and the coating material is fed to the coating gun 3.

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 to atomize the paint supplied from the center of the disk at the edge of the disk (b) a high voltage is applied. A gun-type electrode is known in which an ionized region is formed in the vicinity of the acicular electrode, and paint particles atomized by mechanical means such as air pass through this ionized region, thereby becoming negatively charged. 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 6 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 painting gun 6 is a gun-type painting gun, and a needle-shaped 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 a counter electrode, and is passed through a high voltage generator (not shown) and a coating gas/3. A current is generated in the vehicle body 4.

Then, the negatively charged paint particles pass through the ionization region near the needle electrode and the electric field EK? 8 flies towards the vehicle body 4. L indicates the spraying distance.

5 is a cart, and 6 is a floor conveyor. The floor conveyor 6 is adapted to be driven by a cart 5 hooked thereon. A pair of limit switches on the left and right integrated with the guide rail7.
8 (however, only one side is shown) is provided and is operated by the dogs 2a and 2b of the carriage 2.

That is, when the limit switch 7 is activated, the switching pulp 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 moves forward.

An instruction to change back motion or standby is given.

However, in such electrostatic painting equipment, paint supply is controlled by a limit switch, so it is necessary to move the limit switch every time the car body is changed, or to set the limit switch to the maximum width. In the former case, the movement of the limit switch was difficult, and in the latter case, there was a problem that paint was often sprayed.

This invention i 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 coating 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 pulp in the paint supply path and spraying paint only in the range where the paint exceeds the standard value.

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 composed of a hose 1
4, and there is a solenoid valve 11 in the middle of the hose 14.
is inserted. Paint supply means 10. Solenoid valve 11. The hose 14 constitutes a paint supply path 15. 12 is a high voltage generator. This high voltage generator 12. Paint gun 30
A high voltage circuit 16 is formed including the needle electrode, the electric field E, and the vehicle body 4, and a current (2) flows through it.

The relationship between the current I and the spraying distance is as shown in FIG. 3, and the current corresponding to the reference spraying distance Lp (for example, 30cIIL) is the reference current Ip (for example, 200 μA).

Reference numeral 16 indicates a paint supply control section, which operates as follows.

Set current IH lower than the reference current value Ip (the spray distance LH corresponding to this set current value IH is the reference spray distance Lp)
I(larger) and the current during painting work.
A signal k is output to the solenoid valve 11 only during IH. The solenoid valve 11 switches from the state shown in the figure and cuts off the hose 14 only while the signal k is being input.

Therefore, when the paint gun 6, which is moving at a constant height relative to the car body 4, is away from the car body 4, no paint is supplied to the paint gun 3 (and the paint gun 6 approaches the car body 4). When the spraying distance becomes smaller than the above LH, the current I)
Since the signal k becomes H, the paint supply control section 16 no longer outputs the signal k. Therefore, the solenoid valve 11 is switched as shown in the figure, and paint is supplied to the coating gun B.

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 pulp of the road is opened and the paint is sprayed, the application width 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. 6 is a diagram showing the relationship between spraying distance and current. It is a line diagram showing a relationship. 1... Guide rail 2... Carriage 6... Painting gun 4... Vehicle body (object to be coated) 10... Paint supply means 11・・・
... Solenoid valve 12 ... High voltage generator 16 ... Paint supply control section

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 the 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.