Fluid sprinkling – spraying – and diffusing – Processes – Including centrifugal force or spattering
Reexamination Certificate
1999-09-13
2001-01-30
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Processes
Including centrifugal force or spattering
C239S112000, C239S223000, C239S305000, C239S703000
Reexamination Certificate
active
06179217
ABSTRACT:
TECHNICAL FIELD
This invention relates to a coating method by the use of a rotary atomizing head type coating system, particularly suitable for use, for example, in coating vehicle bodies or the like which require changes of the paint color in the course of a coating operation.
BACKGROUND OF THE INVENTION
Generally, rotary atomizing head type paint coating systems have been in wide use for coating vehicle bodies and the like. In connection with coating operations of by a coating system of this class, there are increasing demands for measures which can reduce the amounts of paint and solvent which have to be discarded as waste each time when changing the paint color in the course of a coating operation, as well as for measures which can cope with as many paint color changes as possible.
Noteworthy as a first prior art in this regard is Japanese Laid-Open Patent Publication No. H8-229446 which discloses a rotary atomizing head type coating system incorporating measures for reducing the amounts of waste paint and solvent and for coping with an increased number of paint colors. This rotary atomizing head type coating system employs paint cartridges of different colors which can be replaceably set in position on the system according to color specifications of a coating object such as vehicle bodies or the like. This prior art coating system is not equipped with a cleaning device for washing off residues of a previous color, and there is unable to fulfill the functions as required of the coating systems of this sort.
There have also been known the so-called automatic coating systems (e.g., as described in Japanese Laid-Open Patent Publication No. S63-175662) which are configured to perform a coating operation automatically for a vehicle body or the like according to a programmed routine. In a prior art automatic coating system of this sort, which is herein referred to as a second prior art for the convenience of explanation, a plural number of paint cartridges of different colors are located in predetermined positions within a working area of a working mechanism such as a coating robot or the like, and automatically changed from one cartridge to another at the time of a change of paint color. Further, in the case of the automatic coating system of the second prior art, in order to permit replacements of paint cartridges (changes of paint color), a hose is connected to the coating system to feed a washing fluid to a rotary atomizing head of the system. Provided internally of the coating system and in communication with the washing fluid hose is a washing fluid passage leading to the rotary atomizing head. At the time of washing off residues of a previous color from the rotary atomizing head, a washing fluid is spurted toward the rotary atomizing head through the washing fluid supply hose and passage.
Further, described in an application, which was internationally published in the WIPO gazette under WO 97/3470, is an automatic coating system which is noteworthy, for example, as a third prior art. The automatic coating system according to this third prior art includes a working mechanism which is located within a coating area, a coating machine having an atomizing unit and supported on the working mechanism, a plural number of paint cartridges which are filled with paint of different colors and interchangeably mounted on the coating system, and a cartridge changing device which functions to support and interchangeably load the paint cartridges on the coating machine.
In the case of the automatic coating system of the third prior art with the arrangements just described, a hose is connected to the coating system to feed a washing fluid to the latter in a manner similar to the above-mentioned second prior art. Provided in the coating system and in communication with the washing fluid hose is a washing fluid passage leading to a rotary atomizing head of the coating system. A washing fluid valve is provided in the washing fluid passage to open and close the same.
Thus, in the above-described coating system of either the second or third prior art, which incorporates a washing device or mechanism for a rotary atomizing head, a washing fluid supply hose is connected to a washing fluid passage which is provided internally of the coating machine. Therefore, it has inherent problems such as difficulties in handling and placing the hose in evasive positions in addition to increases in scale and weight of the coating machine itself.
Besides, in case a high voltage is applied for the purpose of enhancing the paint deposition efficiency, the high voltage could leak to the outside through the washing fluid in the washing fluid passage and the hose.
DISCLOSURE OF THE INVENTION
In view of the problems of the prior art as described above, it is an object of the present invention to provide a coating method by the use of a rotary atomizing head type coating system, permitting to change the paint color at multiple points in the course of a coating operation without necessitating to discard paint as waste.
According to the present invention, in order to solve the above-described problems, there is provided a coating method by the use of a rotary atomizing head type coating system which basically includes: a housing having a coating machine mounting portion on the front side and a cartridge mounting portion on the rear side thereof; a coating machine adapted to be mounted on the coating machine mounting portion of the housing, and having an air motor with a rotational shaft and a rotary atomizing head mounted on a front end portion of the air motor; a feed tube passage hole provided internally of and axially through the rotational shaft of the air motor, and having a front end opened into the rotary atomizing head and a rear end opened into the cartridge mounting portion of the housing; and a plural number of paint cartridges having paint of different colors filled in respective cylinders, and having a feed tube extended axially forward from a front end portion of the cylinder; the coating method being characterized by a sequence comprising: a paint cartridge loading step of loading a selected one of the paint cartridges, setting the paint cartridge cylinder in position in the cartridge mounting portion of the housing, and placing the feed tube of the paint cartridge in the feed tube passage hole; a coating step of supplying paint from the loaded paint cartridge to the rotary atomizing head being put in high speed rotation; a paint cartridge unloading step of unloading the paint cartridge from the housing after finishing a predetermined coating operation; and a washing step of supplying a washing fluid to the rotary atomizing head from front side thereof to wash away deposited residues of a previous color therefrom.
According to the coating method just described, in a paint cartridge loading step, the cartridge cylinder of a color to be used firstly in a coating operation is set in position on the housing of the coating system, with a feed tube of the paint cartridge placed in the feed tube passage hole. In a next coating step, paint is supplied from the loaded paint cartridge through the feed tube to the rotary atomizing head which is put in high speed rotation by the air motor, thereby spraying the supplied paint on a coating object. Upon finishing a predetermined coating operation in the coating step, the paint cartridge is unloaded from the housing in a succeeding paint cartridge unloading step. Further, in a washing step, a washing fluid is supplied to the rotary atomizing head from the front side thereof to wash away deposited residues of a previous color in preparation for a coating operation in a new color.
Further, according to the present invention, there is provided a coating method by the use of a rotary atomizing head type coating system including: a housing having a coating machine mounting portion on the front side and a cartridge mounting portion on the rear side thereof; a coating machine adapted to be mounted on the coating machine mounting portion of the housing, and having an air motor
Matsuda Hidetsugu
Yoshida Osamu
ABB K.K.
Hun Davis
Kashnikow Andres
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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