JPH0157623B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the cleaning of spray heads. More particularly, the present invention relates to a method and apparatus for automatically cleaning a spray head with thinner to remove paint adhering to the spray head, particularly for use in a rotary atomizing coating apparatus.

[Conventional technology]

It is well known that electrostatic coating technology is widely used for coating various articles such as automobile bodies, and that one of the devices used for such coating is a rotary atomization type coating device. . By the way, when electrostatic painting is performed using such a coating device, the paint comes into contact with or adheres to the inner surface of the hub, the inner wall of the head, the tip of the head, and even the outer periphery of the head, causing the paint to drop. A thin film or particles are formed. The presence of such paint contamination is a problem, especially when painting with different colors.
Typically, after applying an electrostatic coating of one color and before applying an electrostatic coating of the next color, a cleaning process, known in the art as a color change cleaning, is performed to remove the thin film or particulate material deposited on the spray head. Paint is being removed. The thinner used to remove adhering paint is a mixed solvent consisting of a solvent, a co-solvent, a diluent, and the like.

Conventional color change cleaning involves applying a thin jet of thinner from a thinner supply tube (usually a metal capillary tube) fixed to the color change cleaning shroud onto contaminated areas on the inner and outer surfaces of the spray head while rotating the spray head. A spray method is used. According to this conventional method, it is possible to spray thinner precisely at a predetermined location on the contaminated portion of the head. However, in this method, the thinner is discharged from the tube, so when the shroud is repeatedly attached and detached for maintenance etc., the thinner discharge position may shift.
The discharged thinner does not get on the inner and outer surfaces of the head and scatters, resulting in thinner droplets adhering to the outer wall of the shroud and the main body of the sprayer. If you change the color and paint with these thinner droplets still attached, the undesirable thing is that the thinner droplets will fall onto the painted surface due to gravity or electrostatic force, causing skin irritation. Paint film defects such as , pinholes, and flickering occasionally occur. Furthermore, this method, which dispenses thinner in the form of a thin jet (so to speak, rod-shaped),
Once you lose your aiming point, the thinner will scatter, so
During construction, it is necessary to accurately determine the positional relationship between the thinner supply tube and the coating machine (particularly its spray head), and the adjustment requires considerable effort.

[Problem that the invention seeks to solve]

As can be understood from the explanation of the prior art described above, the problems to be solved by the present invention include coating film defects caused by thinner scattering in the prior art;
Also, strict alignment between the spray head and the thinner outlet, which was required in the prior art. In other words, an object of the present invention is to provide an improved color change cleaning method and device that does not cause paint film defects due to color change cleaning and that allows easy alignment of the spray head and thinner outlet. .

[Means for solving problems]

According to the present invention, the above-mentioned problems can be solved by using the rotary atomization type coating device after electrostatic coating is performed and before the next electrostatic coating is performed by changing the color. This problem can be solved by a method of cleaning a spray head for a rotary atomizer type coating device, which is characterized by spraying atomized thinner onto the spray head to wash and remove paint adhering to the head.

In carrying out the cleaning method according to the present invention, an excellent cleaning effect can be obtained when the atomized thinner is sprayed particularly toward the tip and outer circumference of the spray head. Moreover, this spraying can be advantageously carried out in an airless manner, that is, without using atomizing air, using a method in which the thinner is atomized at the thinner supply pressure.

Further, according to the present invention, after performing electrostatic painting using a rotary atomizing type painting device and before performing the next electrostatic painting with a different color, the spray head for the painting device can be changed in color. A cleaning device comprising: a color change cleaning shroud; attached to the shroud;
The above-mentioned problems are solved by a cleaning device for a spray head for a rotary atomizing coating device, characterized in that the cleaning device includes a thinner supply tube having a spray nozzle capable of spraying atomized thinner onto the spray head. Can be done.

In the cleaning device according to the invention, in order to obtain an excellent cleaning effect, at least one of the spray nozzles is directed toward the tip of the spray head, and at least one of the spray nozzles is directed toward the outer periphery of the spray head. It is preferable. Furthermore, it is preferable that the spray nozzle itself be an airless type nozzle, that is, a nozzle in which the thinner is sprayed at the supply pressure of the thinner.

〔Example〕

The invention will now be described with reference to the accompanying drawings. For reference, the conventional technology will be explained with reference to Fig. 2 as follows: Fig. 2 shows an example of a rotary atomization type coating device using a conventional airless atomization method. FIG. Reference numeral 1 in the figure is a coating apparatus main body, to which a shaping air attachment 5 and a spray head 2 are attached. This painting equipment has
As shown in the figure, a color change cleaning shroud 7 supported by a shroud support 6 movable by the operation of a cylinder (not shown) is attached, and the shroud 7 also has two thinner discharges. A thinner supply tube 9 with tubes 10a and 10b is attached.

During painting, the color change cleaning shroud 7 shown in FIG. 2 is positioned behind the spray head 2 by cylinder action. The paint from the paint tank (not shown) is supplied from the paint tube 3 to the inner surface of the hub of the spray head (surface D in the diagram), and then travels along the inner wall of the head (surface B) to form a mist at the edge of the spray head. The coating material is electrostatically applied to an object (not shown) in the form of paint particles. Here, the paint particles subjected to electrostatic coating are undesirably affected by the entrained airflow around the head, at the tip of the head (plane A in the figure) and the outer wall of the head (i.e., the outer periphery). (C side in the figure).

After painting is completed and before painting the next color, color change cleaning is performed to completely remove the thin film or particulate paint adhered to surfaces A, B, C, and D of the spray head. During painting, the shroud 7 placed behind the spray head 2 is pushed forward by cylinder action and brought to the position shown in FIG. Thinner introduced from a thinner tank (not shown) through a thinner supply tube 9 is discharged from two thinner discharge tubes 10a and 10b.
The tip (A side) and the outer periphery (C side) of the head, respectively.
discharge in the form of a thin jet toward the surface). Furthermore, the inner surface of the hub (D surface) and the inner wall (B surface) of the head are completely cleaned by a thinner tube 4 that communicates with the thinner tank. The waste thinner after being used for cleaning is collected by the receiving part of the shroud 7, and is continuously discharged out of the system by the thinner waste liquid removal tube 8.

By the way, in this conventional color change cleaning, especially when the thinner discharge angle of the thinner discharge pipes 10a and 10b of the thinner supply tube 9 changes (for example, when cleaning the inner wall of the shroud 7, etc., this may be caused by contact with the thinner supply tube). Since the discharged thinner is in the form of a thin jet (rod), the thinner does not get on the A side or C side of the rotating spray head 2 properly, and some of the thinner becomes droplets. It forms a shape and is thrown off, and is attached to the front opening of the shroud 7 and the front and side surfaces of the shaping attachment 5. Such a phenomenon is undesirable, especially when the coating device is placed above the object to be coated, and must be avoided. This is because during painting following color change cleaning, droplets of thinner adhering to the shroud and shaping attachment fall onto the object to be coated due to gravity, resulting in quality defects such as paint film defects. This is because it causes

FIG. 1 is a schematic sectional view showing a preferred example of a rotary atomization type coating apparatus using an airless atomization method according to the present invention. The construction of this apparatus is the same as that of the apparatus of FIG. 2 described above, except that the thinner spraying section has been improved in accordance with the present invention. The apparatus shown in FIG. 1 is characterized in that spray nozzles 11a and 11b are attached to the tips of thinner discharge pipes 10a and 10b, respectively, used for color change cleaning. The spray nozzles 11a and 11b are airless atomization type spray nozzles that can spray thinner in an atomized state at a thinner supply pressure (usually 1 to 3 kg/cm ² ). Although there is a method in which atomizing air is also used for spraying the thinner, this method is not preferred because the thinner particles bounce off the spray head surface. The airless atomization method used in the present invention not only prevents the thinner particles from bouncing back, but also simplifies the structure by omitting the air hose, and can produce various forms of mist by replacing the spray nozzle. You can get thinner like this.

The work during painting is the same as the apparatus shown in Figure 2. Therefore, description of the work will be omitted here to avoid duplication.

During color change cleaning, the shroud 7, which was placed behind the spray head 2 during the previous painting, is pushed forward by the cylinder action and brought to the position shown in FIG. Thinner introduced from a thinner tank (not shown) through a thinner supply tube 9 is supplied through thinner discharge pipes 10a and 10b from spray nozzles 11a and 11b attached to each of these discharge pipes, respectively. A mist is discharged toward the tip (side A) and the outer periphery (side C) of the head in the form of a mist that spreads toward the end. Furthermore, the hub surface (D surface) and inner wall (B surface) of the head are connected to the thinner tube 4 which communicates with the thinner tank.
Wash. Waste thinner after being used for cleaning is
Similar to the apparatus shown in FIG. 2, the waste thinner liquid is continuously discharged to the outside of the system through the tube 8 for removing waste liquid.

In the color change cleaning according to the invention, it has been found to be advantageous for the atomized thinner discharged from the atomizing nozzle to the atomizing head to have a particle size of about 20 to 100 .mu.m. This is because if the particle size falls below the lower limit, a satisfactory cleaning effect cannot be obtained, and on the other hand, if the particle size exceeds the upper limit, the desired atomization state cannot be obtained.

When spraying atomized thinner into the spray head,
It is unnecessary to contact the entire surface of the head with thinner; it is usually sufficient to cover approximately half of the contaminated area of the head with atomized thinner. Therefore, even if the thinner discharge angle slightly deviates for some reason, the discharge angle can be adjusted by finely adjusting the spray nozzle and adjusting the opening angle of the pattern of atomized thinner that is formed. It is possible to cover the misalignment, and there will be no difference in the cleaning results.

Even if atomized thinner adheres to the shroud opening or shaping air attachment during color change cleaning, the droplet size is small and the entrained airflow around the atomizing head generated by rotation of the atomizing head will dissipate it. Instant vaporization and droplet fall do not occur.

Atomized thinner, unlike traditional rod-shaped thinners, is not blown away by the rotating spray head, and can very easily and completely wet the contaminated area of the head, so it can be sprayed in a very short period of time. A color change wash can be completed. In fact, color change cleaning, which required about 3 to 5 seconds with the apparatus shown in FIG. 2, can be shortened to 1 to 2 seconds with the apparatus of the present invention shown in FIG.

As a modification of the device shown in FIG. 1, it is proposed to attach spray nozzles similar to those 11a and 11b to the tip of the thinner tube 4 as well. It will be understood that by adopting such a configuration, it is possible to prevent thinner from scattering from the inner surface of the hub (surface D) to the front surface of the shaping air attachment 5.

Furthermore, instead of branching two thinner discharge pipes 10a and 10b from one common thinner supply tube 9 and attaching spray nozzles 11a and 11b to each as shown in FIG. It is also proposed to increase the number of spray nozzles to two and attach a dedicated spray nozzle to each. By changing the thinner supply tube to a dedicated type in this way, it will be possible to form a more uniform thinner mist pattern.

〔Effect of the invention〕

As understood from the above description, according to the present invention, the same cleaning effect as conventional color change cleaning can be achieved with a smaller amount of thinner and in a shorter cleaning time, and as a result, Color change time can be shortened.

Further, according to the present invention, when determining the discharge position of the spray nozzle, it is only necessary to align them face-to-face instead of by aligning the points as in the conventional method, so that the thinner discharge pipe and the spray nozzle can be easily set.

Additionally, according to the present invention, the problem of atomized thinner adhering to shroud openings and shaping air attachments during color change cleaning can be ignored, and thinner atomized on the spray head surface can be ignored. It is possible to prevent particles from bouncing back.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a preferred example of a rotary atomization type coating apparatus according to the present invention, and FIG. 2 is a schematic sectional view showing an example of a conventional rotary atomization type coating apparatus. In the figure, 1 is the coating equipment main body, 2 is the spray head, and 3
is a paint tube, 4 is a thinner tube, 5 is a shaping air attachment, 6 is a shroud support, 7 is a color change cleaning shroud, 8 is a thinner waste liquid removal tube, 9 is a thinner supply tube, 10a and 10b is a thinner discharge pipe, and 11a and 11b are spray nozzles.

Claims (1)

[Scope of Claims] 1. After performing electrostatic painting using a rotary atomizing type painting device and before performing the next electrostatic painting to change the color, atomized thinner is applied to the spray head of the painting device. 1. A method for cleaning a spray head for a rotary atomization type coating device, which comprises cleaning and removing paint deposited on the head by spraying. 2. The cleaning method according to claim 1, wherein the atomized thinner is sprayed toward each of the tip and outer circumference of the spray head. 3. The cleaning method according to claim 1 or 2, wherein the spraying of the atomized thinner is performed in an airless manner. 4. A device for color changing cleaning of the spray head of the coating device after performing electrostatic coating using a rotary atomization type coating device and before performing the next electrostatic coating by changing the color, characterized by comprising a color change cleaning shroud and a thinner supply tube attached to the shroud and having a spray nozzle capable of spraying atomized thinner to the spray head,
A spray head cleaning device for rotary atomization type coating equipment. 5. The method of claim 4, wherein at least one of the spray nozzles is directed toward the tip of the spray head, and at least one of the spray nozzles is directed toward the outer periphery of the spray head. cleaning equipment. 6. The cleaning device according to claim 4 or 5, wherein the spray nozzle is an airless nozzle.