Fluid sprinkling – spraying – and diffusing – Electrostatic type – With impeller
Patent
1991-11-06
1992-11-17
Kashnikow, Andres
Fluid sprinkling, spraying, and diffusing
Electrostatic type
With impeller
239690, B05B 504, B05B 508, B05D 104
Patent
active
051636255
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
This invention relates to an electrostatic spray coating machine with a rotary atomizer head, and more particularly to an electrostatic spray coating machine suitable for spraying aqueous and metallic type paints.
BACKGROUND OF THE ART
Generally, the paints designed for electrostatic spray coating are classified into a solvent type paint (an oil paint) which has a relatively large electric resistance, an aqueous type paint (a water paint) which has a relatively small electric resistance, and a metallic type paint with a dispersed metal powder content has a relatively small electric resistance similarly to the aqueous paint. Since the electric resistance of the paint varies depending upon the type or nature of the paint in this manner, it is the usual practice to apply high voltage by a different method for a different type of paint.
More specifically, the component parts such as paint tank and color changing valve are connected to the earth in operation from the standpoint of preventing danger. In this regard, in case of a solvent type paint with a relatively large electric resistance, there is no possibility of the rotary atomizer head being shorted to the earth potential through a paint supply conduit even if a high voltage is directly applied to the rotary atomizer head. Accordingly, the electrostatic spray coating machine for the solvent type paint is generally arranged to apply a high voltage directly to a rotary atomizer head for direct charging of paint particles.
On the other hand, in case of the aqueous type paint or metallic paint which has a small electric resistance, direct application of high voltage to a rotary atomizer head will invite the problem of shortcircuiting of the rotary atomizer head to the earth potential through the paint in the paint feed conduit, failing to charge the paint particles. Therefore, in case of an aqueous paint, it is the usual practice to apply a high voltage to external electrodes which are located in positions radially outward of a rotary atomizer head, forming a corona discharge region forward of the rotary atomizer head thereby to indirectly charge the sprayed paint particles from the atomizer head.
Illustrated in FIGS. 6 to 9 is an electrostatic coating machine of a prior art construction employing the indirect charging system for the aqueous paint.
In these figures, indicated at 1 is a coating machine of the rotary atomizer head type, which is largely constituted by a cylindrical housing 2 formed of a synthetic resin material (e.g., polytetrafluoroethylene), an air motor 3 mounted within the housing 2 and internally provided with an air bearing (not shown), a rotational shaft 4 rotationally driven from the air motor 3, a rotary atomizer head 5 mounted on the rotational shaft 4 on the front side of the housing 2, and a paint feed tube 6 in the form of a metal pipe passed through the rotational shaft 4 to supply paint to the rotary atomizer head 5. An insulate support 7 is projected on the rear side of the housing 2, the insulate support 7 being mounted on a reciprocator or the like. The basic construction of the air motor 3 is known from Applicant's prior application, Laid-Open Japanese Utility Model Application 60-13259, and therefore its detailed description is omitted here.
The reference numeral 8 denotes an annular electrodemounting bracket which is located radially on the outer side of the circumference of the housing 2 and radially outward of the rotary atomizer head. The bracket 8 is supported on the rear end of the housing 2 through support arms 8A. Indicated at 9 are supporters which are formed of a plastic material (e.g., polytetrafluoroethylene) to serve as electrode retainer rods which cover external electrodes 10 as will be described later. Each supporter 9 is provided with a recess 9A at its fore end, and six of this sort of supporters 9 are provided in equidistant positions around the circumference of the electrode brackets 8. As shown in FIG. 9, the external electrodes 10 are axially fitted and retained in the respective su
REFERENCES:
patent: 3393662 (1968-07-01), Blackwell
patent: 4771949 (1988-09-01), Behr et al.
patent: 4872616 (1989-10-01), Behr et al.
patent: 5011086 (1991-04-01), Sonnleitner et al.
patent: 5039019 (1991-08-01), Weinstein et al.
Takayama Shinichi
Tsuboi Yoshihisa
Kashnikow Andres
Merritt Karen B.
Ransburg Automotive KK
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