Rotary atomizing head type coating device

Details Rotary atomizing head type coating device Rotary atomizing head type coating device

1999-09-09

2001-09-04

Crispino, Richard (Department: 1734)

Coating apparatus

With means to apply electrical and/or radiant energy to work...

Electrostatic and/or electromagnetic attraction or...

C118S302000, C118S626000

Reexamination Certificate

active

06284047

ABSTRACT:

TECHNICAL FIELD
This invention relates to a rotary atomizing head type coating system particularly suitable for use in coating objects such as vehicle bodies or the like which require a color change or changes in the course of a coating operation.
BACKGROUND OF THE INVENTION
Generally, a coating systems which is used in coating objects such as vehicle bodies or the like are constituted by a housing, an air motor which is mounted in the housing, a rotary atomizing head which is mounted on a fore end portion of a rotational shaft of the air motor, and a feed tube which supplied paint to the rotary atomizing head. In a coating system of this sort, the rotary atomizing head is put in rotation by the air motor, while paint is spurted into the rotary atomizing head through the feed tube, thereby spraying paint toward a coating object. In the course of a coating operation, it is usually the case that the paint color has to be changed frequently at multiple points for a number of coating objects which are successively transferred toward the coating system.
Therefore, recent developments in this field are focused on coating systems which necessitate to discard only a small amount of paint of a previous color on each color change and which can wash away deposited residues of previous color by the use of a reduced amount of solvent and within a short color changing time, for example, as disclosed in Japanese Laid-Open Patent Publication No. H6-134354 and H7-328493.
Prior art coating systems of this class are equipped with a plural number of paint feed tubes for the respective paint colors to be used, along with a solvent feed tube, and these feed tubes are extended axially and internally of the rotational shaft.
Accordingly, when changing the paint color, firstly the supply of paint of a previous color is stopped and then a washing solvent is spurted into the rotary atomizing head to wash away deposited residues of the previous color therefrom and to prepare for a coating operation in a new color without necessitating to discharge the previous color and without consuming a large amount of washing solvent.
Further, as another example of the prior art, there have been known the so-called cartridge type coating systems which are equipped with a plural number of paint cartridges which are filled with different paint colors and adapted to be replaceably mounted or loaded on a coating system, for example, as disclosed in Japanese Laid-Open Patent Publication No. H8-229446.
In the case of a cartridge type coating system just mentioned, one paint cartridge of a particular color which is selected from a number of paint cartridges of different colors is loaded into a housing of the coating system. Then, paint-extruding air is supplied to the paint cartridge from the side of the housing, thereby supplying paint in the cartridge to a rotary atomizing head of the coating system. At the time of changing the paint color, the paint cartridge itself is replaced by another cartridge of a desired color. Accordingly, it becomes unnecessary to omit a washing operation of a paint supply passage or passages, which has thus far been inevitably required on each color change.
The above-described prior art coating systems, having a plural number of feed tubes passed internally of a rotational shaft, need to place a multitude of feed tubes in the rotational shaft in order to cope with multiple paint colors.
However, it is difficult to place a large number of feed tubes in a rotational shaft of an air motor unless the diameter of the rotational shaft is large enough. It follows that the coating system needs to have an air motor of a large size, which would result in increases in size and weight of the coating system itself. For this reason, the coating system can usually receive only a limited number of feed tubes in the rotational shaft, thereby failing to cope with a large number of paint colors.
Further, in the case of the other prior art coating system of the cartridge type as mentioned above, it has been necessary to refill an unloaded paint cartridge each time when changing the paint color, and, for this purpose, it has been necessary to have paint refilling equipments located in the vicinity of the coating system for a paint refilling work, which is troublesome and time-consuming.
DISCLOSURE OF THE INVENTION
In view of the above-mentioned problems with the prior art coating systems, it is an object of the present invention to provide a rotary atomizing head type paint coating system which permits to change the paint color in a facilitated manner and which can be significantly reduced in both size and weight.
According to the present invention, in order to solve the above-mentioned problems, there is provided a rotary atomizing head type coating system which comprises: a housing including a coating machine mount portion formed on a front side thereof for attaching a coating machine, and a feeder unit mount portion formed on a rear side for accommodating a feeder unit; a coating machine operatively mounted in the coating machine mount portion of the housing, and having an air motor with a rotational shaft and a rotary atomizing head mounted on a fore end portion of the rotational shaft; a feed tube passage hole formed axially and internally of the rotational shaft of the air motor, and having a fore end opened toward the rotary atomizing head and a rear end opened into the feeder unit mount portion of the housing; a plural number of feeder units providing supply sources for a variety of paint colors and being adapted to be replaceably and selectively loaded into the feeder unit mount portion of the housing, each one of the feeder units including a valve receptacle portion accommodating a paint valve and a solvent valve therein, and a feed tube extending axially forward from the valve receptacle portion to supply paint or solvent toward the rotary atomizing head from the paint valve or solvent valve, the feed tube of the feeder unit being placed in the feed tube passage hole when loaded into a feed tube mount portion; paint conduits connected between the feeder units and paint sources of different colors to supply a variety of paint colors separately to the respective paint valves of the feeder units; and solvent conduits connected between the feeder units and a solvent source to supply a solvent to the respective solvent valves of the feeder units.
With the arrangements just described, in a preparatory stage for a coating operation, a selected one of the feeder units is loaded into the feeder unit mount portion of the housing, thereby placing the feed tube of the feeder unit in the feed tube passage hole which is formed internally of the rotational shaft of the air motor. In this state, the paint valve in the feeder unit is opened to supply paint to the feed tube from the paint source through the paint conduit, and spurted into the rotary atomizing head from the feed tube. As a consequence, the paint is atomized into fine particles by the rotary atomizing head which is rotationally driven by the air motor, and sprayed toward a work piece or coating object.
On the other hand, at the time of changing the paint color, the solvent valve in the feeder unit is opened to supply a solvent from the solvent source to the feed tube through the solvent conduit, and spurted toward the rotary atomizing head to wash away deposited residues of the previous color therefrom.
After washing away the previous color, the feeder unit of previous color is unloaded from the feeder unit mount portion of the housing and replaced by a feeder unit of a next or new color. Then, in the same manner as described above, the paint valve is opened to start a coating operation in the new color.
In this instance, preferably the housing according to the present invention is detachably mounted on a fore end portion of an arm of a working mechanism, so that the coating system can be easily replaced by a different type whenever necessary.
Further, according to the present invention, another feed tube passage hole may be formed in the housing in coaxia

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