JPS62289254A - Rotary type atomized-liquid electrostatic spray coating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention The present invention relates to electrostatic spray coating, and more particularly to an electrostatic spray coating device for atomized liquid using rotary atomization.

Conventionally, electrostatic spray application devices equipped with rotary atomizers have been used for a long time. In that case, a conductive sieve cup or disk, usually maintained at a high voltage, is rotated at very high speed, which directs the liquid application material to the central part of the cup or disk, and the surface of the cup or disk under centrifugal force. Moving outward, it leaves these cups or discs from their external edges and becomes sprayed. The atomizing edge of the cup or disk is sharp, so applying a high voltage to the conductive cup or disk ionizes the air in the area of the atomizing edge, causing the atomized liquid to ionize as is well known in the electrostatic spray application field. An electrostatic charge is imparted to the coated particles. It is known that when using conductive spray cups and discs that are kept at high voltage, there is a risk of shock to workers and ignition, especially when flammable paints are used. . This kind of risk is
Briefly, significant electrical energy is capacitively stored in a conductive cup or disc held at a high voltage, and if this cup or disc is inadvertently brought to ground or near a grounding body, said stored energy will be released. This is caused by a rapidly discharging stone. Many methods have been proposed to minimize such risks.

For example, an atomizing cup or disk may be formed of an insulating material except for a conductive skin or layer, such skin or layer may be placed on the surface of the atomizing member, and a high voltage applied to the atomizing edge;
A device configured to ionize it has been proposed. Furthermore, atomization cups or discs using resistive materials have also been proposed. These methods and other conventional methods are each patented by Galatia (
Gauthier) No. 2,926.106, Galatia No. 2.989.241, Schottland (Sch
otland) No. 2,955,565, Juvinall No. 3,009,441, Sed 1acs ik No. 3,010,
478, Galatia No. 3,021,077, Juvinal et al. No. 3.048,498, Pain
t) No. 3,063,642, Points etc. No. 3,0
No. 72,341, Galatia No. 3, 083.121;
Galatia No. 3,128.045, Point No. 3.
No. 178.114, No. 3 of Felici et al.
．． No. 279,429, Schar
No. 3,826,425, Point No. 3,075,706;
Robisch) et al. PCTm International Publication No. W085101
455, etc.

However, the above method is not completely satisfactory for various reasons. For example, a high paint transfer efficiency of 90% or more could not be expected from the spraying device. Paint transfer efficiency refers to the percentage or proportion of coating material that is sprayed from a coating device and is actually applied.

In view of the drawbacks of the conventional methods, an object of the present invention is to provide a safe rotary atomizing electrostatic spraying device with high paint transfer efficiency.

To achieve the above object, the present invention provides an electrostatic spray application device equipped with a rotating atomizer made of an insulating material, which when rotated about its axis of rotation, the liquid paint and a second surface separated from the first surface by the atomizing edge. Further, a circular ring-shaped charging electrode is mounted on the first surface, and a current conducting element is mounted on the second surface electrically connected to the circular charging electrode. A plurality of stationary electrical conductors are provided, each having a free end spaced proximately to the circular current conducting element. The stationary electrode facilitates the transfer of electrostatic energy to the cup electrode when the stationary conductor is energized by a high voltage source, and the paint is directed to the atomizing edge under centrifugal force against the filling electrode. Enables contact charging of the liquid paint applied to the first surface as it flows outwardly beyond the first surface in contact. By minimizing the amount of conductive material used in the rotary atomizer, the electrical energy capacitively stored by the atomizer is kept within safe limits;
On the one hand, the configuration of a plurality of stationary electrodes and the four circular moving current elements associated with said stationary electrodes on the rotating atomizer, and further under the action of centrifugal force as the paint moves towards the atomization edge; High transfer efficiency is provided by contact charging provided by conductive electrodes embedded in the surface of the atomizer through which the paint flows.

According to a preferred method of the invention, the safety of the spray device is
A further improvement can be achieved by forming the circular contact charging electrode, its associated circular current conducting element, and the connection means between these elements from a semiconductor material.

Further according to the invention, and in order to further improve the safety of the spray device, the free end of the electrode that transfers electrical energy to the contact electrode arranged inside the cup as well as the outer ring electrode and the outside of the cup are It is protected from damage and unwanted contact by being placed in a rotating recess.

According to another feature of the invention, designed to increase the compactness of the spray application device, the bearing of the spraying device which houses the drive means for the rotary atomizer is such that the diameter of the intermediate section is smaller than that of the front and rear bearings. An annular cavity is defined between the sections, having a generally cylindrical profile that is significantly smaller than that of the section, thereby locating a liquid paint and flushing solvent valve for controlling the flow of liquid paint and solvent to the rotary atomizer. ing. This allows the liquid paint and solvent valve to be located not only in close proximity to the rotary atomizer, but also within the entire envelope of the support housing the rotary drive assembly for the atomizer. .

To facilitate mounting of the spray device on a post etc., a mounting bracket of the desired design is provided and this plug-
/ ) several spaced apart parallel columns project forward;
These struts are mounted at their forward ends with an atomizer support housing the various valves and rotary atomization drive assembly. According to a preferred method of the invention, one of said struts
The book is hollow and houses an electrostatic energy transfer core between a remote high voltage source and a stationary electrode placed in close proximity to a circular conductive element on a rotating atomizer connected to the circular charging electrode. Transfers high voltage electrostatic energy. According to a preferred embodiment, said hollow column houses a gunn resistor in series with said stationary conductor.

In accordance with another principle of the invention, an annular air ring with a circular array of boats defining a forwardly directed air jet is removably mounted on the front face of the bearing. This near ring has an annular inset in its rear wall that acts as a circular air manifold to distribute air into a circular array of air passages to form air jets and shape the atomized liquid paint. The air ring rear wall further includes an annular inset encasing a single circular conductor to which a high voltage is applied from a remote electrostatic power source. The circular body connects to it a plurality of stationary conductors that transfer electrostatic energy to the charging electrodes of the cup. According to one preferred method, the static z>, t3 body is arranged in a sheath that is removably screwed into a suitably threaded bore in the front face of the air ring.

The sheath may further house a charging resistor in series with the fixed conductor. It has been found that the above configuration is relatively easy to manufacture, assemble, and maintain.

According to another embodiment of the invention, the annular air ring comprises:
The rotary atomizer cup is cap-shaped with an outer surface that is aerodynamically shaped to eliminate eddy currents generated by airflow along the outer surface of the cup. This improves energy transfer efficiency and also reduces clogging of the atomizer by application material by preventing the spray pattern from being pulled back toward the atomizer. The base of the cap is connected to a first cap that is supplied with high voltage from a remote electrostatic source.
The cap is provided with a groove enclosing the circular body, and the other side of one cap is provided with an anti-fG ring disposed in a recess around the cap. This anti-ta ring is designed so that the first circular ring is energized with the same polarity as the charge imparted to the atomized particles of the applied material, in order to improve the efficiency of energy transfer and prevent the atomizing device from depositing the applied material. electrically connected to the thick body.

Instead of using a sheath threaded onto the air ring, other embodiments of the invention include a plurality of stationary conductors and their associated charging resistors embedded within the cap. This serves to protect and stabilize the charging resistor and associated leads, and to shorten the overall length of the atomizing device.Furthermore, according to the invention, the camp preferably has the atomizing cap It has a slightly thickened inset which is arranged and thereby defines a gap between the wall of the inset and the outer surface of the cap. The free ends of the nebulizer cup and the outer circular conductor of the spray cup are respectively placed within the gap.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, the rotary atomized liquid spray applicator of the present invention has a front or forward section 12.
and a rear section 14, between which an intermediate section 16 is arranged. The bearing sections 12, 14, and 16 are generally cylindrical in shape. The diameters of the anterior and posterior bearing sections 12 and 14 are approximately the same. The diameter of intermediate bearing section 16 is the same as that of bearing section 12.
and 14, defining an annular cavity 18 between said sections, within which cavity there is a
As detailed below, various valves can be arranged and installed to control the flow of liquid application material and the flow of solvent to clean the interior and exterior of the rotating atomizing cup.

A rotating atomization cup 20 extends forwardly from the front surface 22 of the forward bearing section 12. An annular ring 24 is removably secured to the front surface 22 of the front section 12 of the support body 10 by bolts, threaded means, or the like.

The ring 24 has a circular air passage or manifold 26 formed on its rear surface, and the front of the ring shapes the atomized liquid paint spray pattern 29 formed on the forward edge or rim 42 of the spray cup 20. Extending are a plurality of circular air ports 28 forming a circular array of air jets.

Extending forwardly from the front section 12 of the support lO is a rotating atomization cup 20. This cup 20 is driveably attached to a shaft 23 so as to be rotatable about its axis. A cup drive shaft 23 extends through the bore 12b of the forward bearing section 12, and a conventional commercially available air or ball bearing 25 extends within a suitably configured bearing cavity or bore 27 of the intermediate bearing section 16. It is located in The shaft 23 is conventionally available on the market.
It is driven at its rear (to the left in FIG. 2) by a rotary actuator 31, such as an air-driven turbine, which actuator 31 is located behind the bore 31a of the rear bearing section 14 or the bearing 25 of the turbine cavity. ing. Support 1
A liquid application control valve 33 mounted on the rear surface of the flange-defining portion of the front section 12 of the support 10 controls the application nozzle 30 through a passage 32 formed in the front section 12 of the support 10.
Control the flow of liquid application material to. Leaving the nozzle 30, the slightly pressurized liquid paint flows into an annular cavity 34 formed in the rear section of the cup 20.

Under centrifugal force due to rotation of cup 20 by drive shaft 23, liquid application material within annular cavity 34 passes through a series of paint passages 36 in radial cup wall 20c, radially outwardly and forwardly. It flows out towards the cup cavity 38. Within the forward lamp cavity 38, the liquid paint moves radially forward along a first surface defined by the inner cup wall 40 toward the forward atomizer 42 of the cup 20, where the paint is subjected to centrifugal force. is atomized to form a spray pattern 29. A flat circular ring-shaped charging electrode 46 embedded in the interior wall 40, connected to a conventional electrostatic high voltage source (enclosure) as described below, allows liquid application material to flow from the passageway 36 in the wall 20c. Contact causes the liquid application material to become electrically charged as it passes through the electrode toward the forward spray edge 42 of the cup where the liquid is redirected and atomized to form the spray pattern 29.

``A mounting bracket 50 is arranged at the rear of the support 10 and spaced therefrom.The bracket 50 has a circular plate 52 and a rearwardly extending collar 54.These circular plates 52 The collar 54 is provided with a through hole into which a circular post 56 suitably supported by a spray reciprocating device, fixed pedestal, etc. can be positioned.

A set screw 58 is threaded radially into the wall of the collar 54.
is provided, thereby fixing the bracket 50 to the post 56.

Between the circular plate 52 and the rear face 60 of the rear section 14 of the support 10 are several mounting posts or struts 62.
64 and 66 extend.

The struts 64 and 66 are suitably fixable to the circular plate 52 and to the rear wall 60 of the rear section 14 of the support 10. For example, the struts 64 and 66 can be threaded at their forward ends and into threaded bores suitably provided in the rear wall 60 of the rear section 14 of the bearing 10. .

The struts 64 and 66 have a reduced diameter section at their rear ends, which diameter section means that they are positioned rearward of the rear face 55 of the plate 52 (to the left as viewed in FIG. 1). It extends protrudingly through a suitably provided bore in plate 52.

By means of threads in the reduced diameter portions of the rear ends of struts 64 and 66 that project rearwardly of plate surface 55, the rear ends of struts 62 are threaded as described below using nuts. Similarly, the rear ends of columns 64 and 66 are attached to plate 5.
It can be fixed at 2.

The strut 62 has a reduced diameter section 62 at its rear or left hand end.
c, which portion extends behind the surface 55 thereof through a suitable bore in the provisional 52.

Oak) 62d is screwed onto the support end portion 62c to form the support support 62.
is fixed to the plate 52. The bearing post 62 extends forwardly at its forward end through a suitably provided bore 70 in the rear section 14 of the bearing 10 towards the rear wall 12a of the forward bearing section 12. The frontmost part 62 of the column 62
a has a reduced diameter that threadably engages a suitable threaded bore 72 formed in the rear face of the forward bearing section 12.

The column 62 has an axial inner hole 62b, and a high voltage insulated cable 74 whose rear end is connected to an electrostatic high voltage power source (circuit) is provided inside the hole 62b. This cable 74 has its forward end 74a connected to Gunn resistor 76. Electrical conductor 78 extends between the forward ends of the gunn resistor to energize electrode 46 as will be discussed in more detail below.

As shown in FIG. 1, a dump valve 80 mounted on the front wall 57 of plate 52 is connected to liquid application valve 33 via flexible duct 82 and to waste receptacle 86 via duct 88. .

The dump valve 80 acts to redirect the flow of cleaning solvent from the applicator valve 33 during a color change operation in a manner known in the art.

In addition to the application control valve 33, solvent valves 90 and 92 are provided on the rear face 12a of the flange-defining portion of the forward bearing section 12.
are fitted and these valves control the flow of solvent into and out of the rotating atomizing cup 20, as described below and shown in Figures 3.4.7 and 8, respectively. . The valves 90 and 92 are located within the annular cavity 18.

The rotating atomizing cup 20, best shown in FIG. 2, includes a frustoconically shaped tubular section 20a and a hub 20b, which members are connected by a radial wall 20c, together forming a rear annular cavity 34 and a front annular cavity 34. A cavity 38 is defined. The non-uniform cross-section of this tubular section 20 increases along its axis in the direction of the atomization edge 42. The hub 20b has a tapered inner bore 2Of which is a slip fit in a similarly tapered portion 23a of the drive shaft 23. The front end 2 of this drive shaft 23
3b is threaded and threadably receives a locking nut 100 which properly secures the hub 20b of the cup 20 to the drive shaft 23. Embedded in the outer surface 20d of the frustoconical section 20a of the cup 20 is a circular current-conducting flat ring element 102, preferably made of semiconductor material. This ring element 102 is electrically connected to a flat electrode 46, preferably made of a semiconductor material, via a series of conductive means in the form of pins 104 located in bores provided at appropriate locations in the cup section 20a. Ru. These bottles 104 are preferably made of semiconductor material and their opposite ends are connected to the ring 102.
and is in electrical contact with the opposing surface of the electrode 46. cup 2
0 is the naphto 100, shaft 23, bearing 25, annular ring 24, support 10, rotary actuator 31, valve 33.8
0.90. and 92, and associated fluid ducts, mounting brackets 50, as well as equipment struts 62, 64, and 66, preferably of insulating material, thereby dissipating electrical energy capacitively stored in the spray application equipment. Minimized.

The insulating material used for the cup 20 is American 1. C.I.

PEEK (polyether ether ketone) is preferred and other insulating elements are available from Erta Inc. of Malvern, Pennsylvania.
Preferred is ERTAI, YTE (polyester) commercially available from Orpora ted.

Surrounding the bracket 50 and support 10, as well as the various valves, is a tubular housing, best shown in FIG. 1, which encases the various operating components of the atomizer. This housing is preferably formed from an insulating material.

The liquid application valve 33, which may be conventional, preferably includes a valve body 120 with a diametrically stepped bore 122 having a bore 126 at its forward end. A valve seat insert mount 124 with an axial passageway 128a is disposed within the bore thereof, the passageway being formed in the forward end of the reciprocating rotor l-132. finished ball valve element 130
The rod is always blocked by the shaft 132
The valve is constantly biased forward to close the valve by a spring-loaded pneumatic piston 134 fixed to the rear end 132a. Spring 135 always urges piston 134 forward (to the right in FIG. 2). The air chamber 136 is located in the valve body 12
It is connected to a source of pressurized air via a passage 138 in the rear wall of the 0. When pressurized air is supplied to the air chamber 136 via the passage 138 under the control of means not shown,
Piston 134 is driven rearward (to the left), releasing ball valve element 130 against the valve seat of valve seat insert 128 and connecting passageway 128a to liquid application chamber 142. The application chamber 142 communicates with a pressurized liquid paint source (encircle) via a passage 144 formed in the wall of the valve body 120 that adjoins a paint supply advance pipe 145.

In this way, pressurized air is introduced into the cavity 136 via the air passage 138, driving the piston 134 rearwardly and unseating the valve ball element 130, which causes the coating chamber 142
The pressurized liquid paint passes through passage 128a to passage 32 in forward bearing section 12, where it passes under pressure through nozzle 3.
0 into the rear cavity 34 of the rotating cup 20. As explained above, the liquid applied material in the rear cavity 34 passes over the flat ring electrode 46 and into the front cavity 38.
It flows through the passage 36 along the inner wall 40 of the cell, where it becomes electrostatically charged. Finally, this charged electrostatic paint has a cup of 20
is atomized, or atomized, at the front edge 42 of the spray pattern 29 to form the spray pattern 29.

Air cavity 136 and application cavity 142 are provided with suitable seals 150 to permit axial reciprocating movement of rod 132.
Separated by The cavity 142 of the valve 33 is connected to the conduit 8 through a passage 152 formed in the wall of the valve body 120.
2 and is ultimately led to a waste receptacle 86 via a dump valve 80 and a conduit 88. The dump valve 80 is similar to the valve 3 except that it has only one outlet passage for flowing liquid application material in addition to a single inlet passage.
The structure is almost the same as that of 3. The dump valve 80, like the valve 80 described above, is pneumatic and is therefore connected to the air hose 80a.
A controlled pressurized air source (encircle) is connected to the valve via the valve.

As previously explained, the shaping of the atomized liquid paint spray pattern 29 ejected from the forward edge 42 of the rotary atomizing force 7 20 consists of a plurality of circular axial lines forming forwardly projecting air jets. The extending boat 28 is formed exclusively by a circular air passage 26 formed within the annular ring 24.

To provide pressurized air to the circular air passage 26 formed within this annular ring 24, the forward bearing section 12 is provided with a passage 160 that communicates with the circular air passage 26 at its forward end. and hose 1 at its rear end.
62 to a suitable source of pressurized air. The airflow within this hose 162 is conventionally regulated by control means, not shown. When hose 162 is supplied with pressurized air, the air is ejected forwardly from circular boat 28 under pressure to shape a spray pattern 29 of electrostatically charged atomized liquid paint particles as desired.

If it is desired to change the color of the liquid application material sprayed from the apparatus of the invention, a solvent is introduced into the boat 144 of valve 33 and valve 80 is opened in a manner known in the art. This solvent flows through and cleans valve 33, passage 32, and nozzle 30, and also passage 152 and hose 8.
2 to the dump valve 80, further passes through the dump valve,
It flows into waste receptacle 86 via hose 88 .

Solvent cleaning of the outer surface 20d of the liquid application material associated with the color change is accomplished by a solvent nozzle 170 threaded into a suitably provided lumen 172 in the front surface 22 of the forward bearing section 12. The rear end of the passage 172 is connected to the output port 90a of the solvent valve 90. An input port 90b of the solvent valve 90 is connected to a solvent hose 174 leading from a suitable pressurized solvent source. This solvent valve 9
0 has almost the same structure as the dump valve 80, and like the dump valve 80, a spring-type air-operated piston 90e.
A pneumatic ball valve element 90c is provided at the front end of the rod 90d, which is controlled by a pneumatic ball valve element 90c. A controlled source of pressurized air is connected to the valve 90 via a suitable air hose 176 to operate the valve as desired.

As a concomitant of the color change, the rear cup cavity 3
A solvent nozzle 94 and a valve 92 are provided, as shown in FIG.
It is substantially equivalent to that shown in FIG. 4 for cleaning the outer surface of a. The only difference between the solvent cleaning nozzle 94 and valve assembly 92 for cleaning the interior of the cup 20 described above and the nozzle 170 and valve 90 for cleaning the exterior of the cup is that the nozzle 94 for cleaning the interior of the cup is in the front. It projects from the front surface section 22a of the bearing section 12 into the rear opening 34 of the cup 20. The adjustment of the various valves for effecting the color change, the cleaning of these valves, nozzles, associated passages, hoses, etc., and the cleaning of the inside and outside of the atomizing cup are carried out in a manner known in the art. It will not be detailed here.

A pressurized solvent valve 180 leads to a hose 182 which leads a solvent delivery hose 174 to a valve 90 which controls the flow of solvent to wash the exterior of the cup 20 and a solvent delivery hose 175 to a valve 90 which controls the flow of solvent to clean the exterior of the cup 20. 20 internal cavities 3
It is branched to lead to 4.

A source of pressurized air 185 is connected to hoses 186 and 188;
These hoses drive and brake the turbine rotor, then the shaft 23 and finally the atomization cup 20,
The air enters the turbine that applies the brakes. hose 190
exhausts waste gas from the turbine 31. hose 186
and 188 of the air turbine 31 and thus the output shaft 23.
The speed of the rotating atomizing cup 20 can therefore be controlled as known to those skilled in the art.

An air hose 192 connected to a selectively operable pressurized air source cleans the interior of the rotating atomizing cup 20 with a solvent valve 9
Control 2. This air hose 192 is connected to the solvent valve 90 to control its operation. The solvent valve 92 functions similarly to the air hose 176 connected to the paint valve 33 and the air hose 138 that controls its operation.

To minimize build-up of coating material on the surface of the soyaft 23, air purging means are provided to provide a positive air flow to the rotating atomizing cup 20 along the shaft. The air purging means preferably comprises a boat 300, as shown in FIG. 2, mounted on the rear wall 12a of the forward support section 12 and used for connection to an air supply line. This air supply line supplies air from passage 302 into the space between forward support section 12 and shirt l-23 to discharge boat 304. The air acts to provide a positive air purge along the shaft 23 towards the cup 20 to prevent paint from flowing back along the shaft into the bearing 25. .

High voltage electrostatic energy is transferred from electrode 78 at the output of Gunn resistor 76 to semiconductor ring 10 via the path described below.
2 (and finally to semiconductor electrode 46 via semiconductor pin 104).

The above-mentioned path now includes a four-conducting spring contact 200 located at the forward end of a bore 72 formed in the forward bearing section 12 and a conductive spring contact 200 that is a slip fit into the bore formed in the forward bearing section. body 202 and rear wall 2 of annular ring 24
The electrode ring 204 embedded in the annular fitting portion formed in the ring conductor 204 and the semiconductor ring 1
02 and several parallel circuit paths connected between the two. The series circuit path between rings 204 and 102 includes a) a conductor 212 connected between resistor 210 and ring 204; A resistor ffW210 is provided between the conductor 214 and the conductor 214 extending from the end. An insulating sheath 216 having an internal or rearward end threaded into a suitably threaded bore of the annular ring 24 includes a resistor 210, a conductor 212, and four bodies 214 projecting from the forward end of the sheath. is covered. An insulative sheath 218 , comparable to sheath 216 , is mounted spaced circumferentially around annular ring 24 on either side of this sheath 216 .
and 220 are resistors 218a (
3) and 220a. The resistor 218a is
a) an outer conductor 218b extending from the forward end of its associated sheath toward and in close proximity to the semiconductor ring 102; and b) connected to the conductive ring 204. It is connected between four electric bodies 218c that transmit electrostatic voltage to resistor 218a. The above resistor 23220
a) a conductor 220b extending from the forward end of its associated sheath toward and proximate the semiconductor ring 102; and b) a resistor and a conductor Electrical conductor 22 connected between rings 204
0c. The above conductor 214.218
b, and the front protruding end of 220b is the semiconductor ring 10
2, which allows the high voltage to pass through the insulated cable 74, Gunn resistor 76, conductor 78, spring 200, conductor 202, ring conductor 204, and
When applied to the protruding end through resistor pairs 210/212. The outwardly and forwardly flowing liquid application material is transmitted across the gap to the semiconductor ring 102 and finally to the ring electrode 46 via the pin 104 for contact charging.

Compared to using only a single conductor, the paint transfer efficiency is improved by using three circumferentially spaced conductors 212, 218c,
and 220c was found to be enhanced. The use of multiple conductors in this manner improves transfer efficiency and is clearly necessary if high transfer efficiency is desired.

Gunn resistor 76 can have a resistance that varies according to the operating range of the electrostatic power source that energizes cable 74 . If the operating range of the electrostatic power source is between 59 kV and 125 kV, the Gunn resistor preferably has a resistance of 75 megohms. The resistors 210, 218a, and 2
Although the 2 oa can also have variable resistors, each such resistor preferably has a resistance of about 12 megeohms.

The insulated cable 74 may take many forms, but is described in 198 by Hastinges et al., assigned to the assignee of the present application and incorporated herein by reference.
A cable having a conductive core 74b made of silicon carbide in accordance with the disclosure and claims of U.S. Pat. Semiconductor ring 102, vial 104, and electrode 46 are made of RYTON (polyphenylene sulfide (PPS)), which is commercially available from Phillips.
It is preferable that the semiconductor material be made of semiconductor material, but other semiconductor materials may also be used.

Further, and although not preferred, ring 102, bottle I
O=1, and/or electrode 46 can be made from a conductive material. However, when made of conductive material, the ability of rotating atomizer cup 20 to capacitively store electrical energy is greater than that when ring 102, pin 10.1, and electrode 46 are made of semiconductor material. If necessary, conductive elements 78.200.202.204.2
12.214.218b and 218C1 further 220b
and 2200 can be fabricated from semiconductor materials rather than conductive materials. Therefore, and in order to minimize the electrical energy capacitively stored in the spray device of the invention,
All elements of the atomizer are constructed of semiconductor and/or conductive materials to convey electrostatic energy at high voltage from a remote power supply (circuit) to the paint charging electrode 46 of the rotating atomizer cup 20. Therefore, it is preferable to use an insulating material.

In a preferred embodiment of the invention, the rotating atomizing cup 2
Although 0 has been described as having a frustoconical shape, it will be apparent to those skilled in the art that other shapes may be utilized without departing from the spirit and scope of the invention.

Valves 33.80.90 and 92 are generally manufactured by Hastinges (H.
3,870,233.

Figures 10 and 11 refer to other aspects of the invention herein.
This will be explained using the example of the pond shown in the figure.

Other than the differences described below, this other embodiment is substantially the same as the first embodiment described above, and therefore like parts will be assigned like reference numerals.

As shown in the figures, another embodiment of the rotary liquid jet g14 fabric device of the present invention includes a support lO having a front or forward section 12. As in the case of the first embodiment,
An annular cavity 18 is located at the rear of the front section 12. Disposed within the cavity 18 are various valves for controlling the flow of the liquid application material and the solvent for cleaning the interior and exterior of the rotary spray cup 20, as will be described in detail below.

A rotating atomization cup 20 extends forwardly from the front surface 22 of the forward bearing section 12. A cup 400 is removably secured to the front surface 22 of the forward section 12 of the bearing 10, such as by bolts or threaded engagement, and the cup 400 has a generally convex outer surface 402 and at least a portion of the atomization cup 20. The fitting part 404 is disposed at the center where is arranged and is tapered inward. cap 400
includes a base 406 having a generally circular air passage or manfold 26 formed therein. Gasket 408 includes a suitably sized and suitably positioned aperture, and includes a suitably sized and suitably positioned opening to seal the front surface 22 of the forward section 12 of the bearing 10.
and cap 400 to provide adequate sealing for air and solvent passages communicating between forward section 12 and camp 400, as will be described below. Similar to the annular ring 24 of the first embodiment, the cap 400 includes a plurality of circularly disposed air ports 28 forming a circular array of air jets surrounding the rotating atomizing cup 20 and at the forward edge or rim 42 of the atomizing cup 20. It serves to shape the formed atomized liquid application spray pattern 29 and direct it toward the workpiece to be coated as previously described.

As already noted, the front section 12 of the bearing 10
A rotary atomizing cup 20 extends forward from the. The cup 20 is rotatably mounted around a shaft 23 of a rotary actuator (circuit). The cup drive shaft 23 is connected to the inner bore 12 of the forward bearing section 12.
It extends through b. As in the case of the first embodiment,
A liquid application control valve 33 is mounted on the rear of the forward section 12 to control the flow of liquid application material to the application nozzle 30. Exiting the nozzle 30, the slightly pressurized liquid paint enters the cup 20 and passes through it as already explained in the first embodiment.

Inside cavity 18 and forward bearing section 12
In addition to the application control valve 33, a single solvent valve 412 is mounted on the rear side of the valve, replacing the dual internal and external solvent valves 90,92 of the first embodiment. This valve 412 controls the flow of solvent into and out of the rotating atomizer cup 20, as explained below.

The diameter of the frustoconical rotating atomizing cup 20 increases along the axis of the cup in the direction of the atomizing edge 42.

Embedded in the outer surface 20d of this frustoconical cup 20 is a circular current-only flat ring element 102, preferably made of a semiconductor material. According to one aspect of the invention.

For example, the ring element 102 is substantially completely contained within the recess 404, with the cup 20 disposed therein;
This reduces the possibility of personnel or objects coming into contact with the impact hazard element 102. 1st
As in the embodiment described above, the ring element 102 is electrically connected to a flat charging electrode disposed on the inner surface of the cup 20 as described above. A housing 416 is used to enclose all operating elements and various conduits serving application materials, solvents, and waste, and high voltage electrical cables are provided in the first
It is preferably disposed rearwardly through a suitable opening (circuit) in the rear mounting bracket rather than through the side wall as shown. This is to keep the conduits and cables as far away as possible from the spray pattern 29 that emerges from the edge of the atomization cup 20 to prevent build-up of application material on them. This gives a more glossy, uniform and clean appearance.

If it is desired to change the color of the liquid application material sprayed from the apparatus of the invention, the application valve 33 is flushed with solvent using a dump valve as already described. According to another embodiment of the present invention, cleaning of the interior and exterior of the atomization cup 20 of the liquid application material with eight agents (in the case of color change) is carried out using a white solvent valve 412. For this purpose, the valve 412 communicates with the bore 420 of the bearing section 12. The lumen 420 includes a pair of bifurcated lumens 422,424. One branch bore 422 is connected to the nozzle 32 to clean the interior of the cup 20, as previously described. The other branch lumen 424 extends therefrom through a suitable opening in gasket 408 and abuts lumen 426 in cup 400 . The bore 426 includes an outlet boat 428 in the wall of the inwardly tapered recess 404 arranged to clean the exterior 20d of the cup 20.

Valve 412, described above, is constructed substantially identically to dump valve 30, as previously described, and is operated by a controlled pressurized air source to simultaneously clean the interior and exterior of cup 20 with solvent prior to color change or periodic cleaning.

According to the first embodiment, purge air was provided to minimize the buildup of applied material on the shaft 230 surface. According to another embodiment, the bearing 25 was an air bearing.

This means that normal air leakage from the air bearing (circuit) is caused by space 3.
Since it flows along the shaft 23 like the air purge means of 0B, the first embodiment eliminates the need for a separate purge air passage, such as the passage 302 already described. This leakage air flow provides a positive air purge along the shaft 23 towards the cup 20, thereby preventing paint from moving back along the shaft into the bearing (circuit).

Here, the inner wall 20 of the atomization cup 20 according to another embodiment
The path for high-voltage electrostatic energy flowing from the charging electrode 102 and the Hegan resistor 76 buried in d will be explained in more detail. An annular conductor 430 that substantially envelops the cap 400 is disposed in an annular stepped groove 432 cut into the base or rear portion 434 of the cap 400. This conductor 430 can be attached to a larger stage using a suitable adhesive sealant such as epoxy. 1 to 1! It is secured within the groove 432 by a stopped insulating ring 436. The conductor 430 is connected by soldering, brazing, or other suitable means to a conductive disk 438, preferably made of brass or other conductive, corrosion-resistant material.

The disk 438 is fitted into a recess 440 of an electrically insulative bushing 442, which in turn is partially fitted into the front end of the support post 62 which houses the gun resistor 76. The opposite end of this bushing 4420 fits into a pocket in ring 436. The bushing 442 includes an axial bore 444 that receives the cylindrical projection 446 of the strut 62. Pillar end 62a and protrusion 4
46 includes a bore 448 that communicates with gun resistor 76. This bore 448 includes a conductive spring contact assembly 45.
Two hollow tubular support portions 450 are received. This bearing portion 448 has a plunger 45 with a head 458.
6, this head 458 abuts the disc 438 when the base of the bearing portion 450 abuts the gun resistor 76, thereby creating good electrical contact between the gun resistor 76 and the disc 438. and the above disk 4
38 is then connected to an annular conductor 430.

Electrostatic energy is transferred from the charging electrode 10 to the charging electrode 10 by three charging resistors 210 of equal nominal resistance electrically connected in parallel between the charging electrode 102 and the conductor 430.
2. According to another embodiment, the charging resistors 210 are physically mounted within the cap 400 at regular circumferential intervals. All of the resistors 210 are a slip fit within a bore 460 that communicates with the conductor 430 and is located within the fitment 404 of the cap 400 in which the atomization cup 20 is placed.

Each of these bores 460 intersects with a recess 404 at a position opposite the ring element 102 of the atomization cup 20;
This causes the free end 462 of the charging resistor to act as an electrode that is closely spaced from the semiconductor ring element 102. By embedding the charging resistors 210 within the cap 400, the present invention acts to significantly protect these resistors from being damaged or misaligned by accidental shock. Additionally, because the electrode leads 462 are located within the recess 404, the likelihood of these leads coming into contact with the employee or object is reduced, thus reducing electrical shock or mechanical damage. Opposite leads 464 of charging resistor 210 pass through the reduced diameter portion of lumen 460 that intersects groove 432, and lead 46 at this intersection.
4 is a conductor 43 with a semicircle or other suitable means.
Connected to 0.

In this manner, high voltage electrostatic energy is conveyed to Gunn resistor 76 by high voltage cable 74 as previously described. This in turn spring contact 452 and disc 43
8 to conductor 430. From this conductor 430,
Electrostatic energy is transferred to the charging electrode 102 of the atomizing cup by three charging resistors 210, where the resistors 210 are connected to the free end 462 of the electrode or resistor.
and the outer ring element 102 of the atomization cup 20 and the cap and the conductor 430 are electrically connected in parallel. This electrostatic energy is then transferred to the electrode 462.
and the semiconductor ring element 102.

This electrostatic energy is used to charge the coating material as in the first embodiment.

The resistance values of gun resistor 76 and charging resistor 210 are selected as described above. As in the embodiments already described, and in order to minimize the electrical energy capacitively stored in the spray device of the invention, all components of the spray device are rotary atomized from a remote source (circuit). Preferably, it is made of an insulating material, except for those made of semiconductor and/or conductive materials to transfer electrostatic energy at high voltages to the paint charging electrodes 102 of the cup 20.

The other embodiments of the rotary atomized liquid spray system of the present invention include a spray pattern 2 directed forward toward the workpiece to be coated.
The present invention has several features that assist in spraying the spraying device 9 and prevent the accumulation of coating material on the spraying device itself, thereby increasing the efficiency of energy transfer and reducing fouling of the spraying device. One such feature is the formation of an array of forwardly directed air jets surrounding the spray cup 20 to direct the spray pattern 29 toward the workpiece.
The plurality of air boats 28 that spray and shape the air have already been described. Furthermore, according to the invention it is preferred if the spray device of this embodiment furthermore has at least one of the additional features described below.

Atomization cup 20 is surrounded by electrostatic repellent means, which is in the form of a substantially continuous conductive or, more preferably, semiconducting ring 470. Above ring 47
0 is embedded in a groove 1172 cut into the outer surface of the cup 400, 102, so as to be substantially flush with the outer surface of the cup 400 and not interfere much with its outer shape, for reasons that will become clear later.

The ring 470 is electrically connected directly to the conductor 430 by an isoelectric pin 474, thereby energizing the ring 470 with a high voltage charge of the same polarity as the charge carried by the paint particles. This facilitates movement of the spray pattern away from the spray device and towards the workpiece to be coated.

It has been found useful to increase transfer efficiency and avoid build-up of paint material on the spray device by avoiding air swirls that tend to inhibit forward movement of the spray pattern 29. Another important aspect of the invention is provided by providing the outer surface 402 of the cap 400 with a curved aerodynamic profile as shown. The front portion of the camp 400 defines a circular dome having a domed outer surface 402 and a central inset 404 in which the frustoconical atomization cup 20 is placed. There is no believed to be a limit to the degree to which cup 20 fits within cap 400 to avoid reverse air swirl. In fact, the inset 404 may be omitted, since the outer surface 402 only needs to lie almost completely behind the cup 20. However, as previously described, the cup 20 is within the cap 400 about 1/2 to 2/3 of its entire length so that the conductive ring 102 and electrode 462 are protected. It is preferable. The fitting portion 404 is tapered inward to be slightly larger than the wall of the cup 20, so that the gap between the cup 20 and the fitting portion 404 is slightly narrower at the base than at its mouth. ing.

The transition edge between the tapered inset portion 404 and the outer curved surface 402 is not sharp, but rather has a large radius as shown. This aspect of the invention will become more apparent from the theory of operation provided below.

The atomizing cup 20 rotates at an angular velocity sufficient to atomize the coating material, typically between to,ooo and 40,000RPM, so that the atomizing edge 42, which has a larger diameter than the base portion 480, Rotates at surface velocity. The air surrounding the cup 20 causes frictional resistance in the cup 20.
tends to move with the surface of the cup 20, creating a pressure gradient along the outer wall 20d of the cup 20, which
20d and induces an air flow generally parallel to the outer wall 20d from the base 480 toward the edge 42. This air flow creates a partial vacuum in the area near the base of the cup, so that the constituent air flow is believed to flow inwardly along the walls of the recess 404 toward the base 480 of the cup 20. The shape of the cap 400, and in particular the shape of its outer surface 402, is selected such that the constituent airflow flowing along its surface under normal operating conditions is approximately laminar. This is thought to prevent the generation of eddies near the cup 2o,
Without this, vortices would occur that would send the coating material back into the spray device rather than directing it to the desired substrate.

[Brief explanation of drawings]

1 is a side view, particularly in cross-section, of a rotary atomizing liquid spray applicator of the present invention, and FIG. 2 is a cross-sectional view of the front section of the rotary atomizing liquid spray applicator shown in FIG. 1 is a side view illustrating the general relationship of the atomization cup and its drive, the air jets that shape the atomized paint spray pattern, the high voltage circuitry, and the valves associated with the liquid paint flow path; Figure 3 is a cross-sectional view taken along line 3--3 of Figure 2 showing the general arrangement of the main parts of the liquid paint and solvent flow paths to the rotating atomizing cup and their respective valves; , the main part of the air path that shapes the liquid paint spray pattern, and the isoelectric body that applies high voltage to the ring-shaped liquid paint charging electrode installed in the atomization cup. 3 is a cross-sectional view taken along line 4-4 of FIG. 3, illustrating the solvent flow path and valve arrangement for cleaning the exterior of the rotating atomizing cup; FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 6 is a sectional view taken along line 6-6 of FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 1, showing the liquid-applied material and 8 is a cross-sectional view taken along line 8-8 of FIG. 9 is a cross-sectional view taken along line 9--9 of FIG. 1, showing the atomizer rear support section, strut, and Various air and solvent nozzles are illustrated, FIG. 10 is a front view of another embodiment of the discharge nozzle of the rotary atomization spray applicator, and FIG. 11-11 is a partial cross-sectional view. [Explanation of symbols of main parts] 10... Support body 12... Front section 14... Rear section 16... Intermediate section 18. 34... Annular cavity 20... Rotating atomization cup 22. . . . Front face 24 of the forward section 12 . . . Annular ring 25 . . . Bearing 26 of the turbine cavity . ... Rotary actuator 31a ... Bore 32.36.1 of rear section 14
38, 144, 152, 160° 302...Passage 33...Liquid application control valve 38...Front cup cavity 40...Inner cup wall 42...Front sprayer 2-ji 46... Charging electrode 50... Mounting bracket 52... Circular plate 54... Collar 56... Post 58... Set screw 60... Rear surface of rear section 14 62.64.6
6...Mounting post or strut 62C...Reduced diameter portion 62d, 100...Nut 70...Threaded lumen 74...High voltage insulated cable 76...Gun resistor 78. 202, 212, 218b, 218c, 220b
, 430...Conductor 80...Dump valve 82...Flexible duct 86...Waste receptacle 102...Ring element 104...Bin 120...Valve body 122...Within stepped diameter Cavity 124... Valve seat insert mount 128... Valve seat insert 130... Ball valve element 132... Reciprocating rod 134... Piston 136... Air chamber 142... Liquid paint chamber 150 ... Seal 162.174, 176.192 ... Hose 185.
... Pressurized air source 204 ... Electrode ring 216, 218, 220 ... Exterior 300, 304 ... Boat 400 ... Cap 404, 440 ... Fitting part 412 ... Solvent valve 416 ... ...Housing 438...Conductive disk 442...Bushing FIG, 2 FIG, 3

Claims (1)

[Claims] 1. A rotary atomized liquid electrostatic spray application device comprising: a support of an insulating material having a front, middle, and rear section; and a rotating atomizer of an insulating material having an axis of rotation. an atomizer comprising a first surface through which liquid paint can flow outwardly against an atomizing edge of the atomizer when the atomizer is rotated about the axis of rotation; a second surface separated from the first surface;
a circular ring-shaped charging electrode mounted on the first surface surrounding the axis of rotation; and a circular current conducting element mounted on the second surface surrounding the axis of rotation. a means mounted on the rotary atomizer for electrically connecting the circular electrode and the current conducting element; and a support for driveably mounting the rotary atomizer on the front section of the support. a driving means that is incorporated into the body and rotates the rotary atomizer around the rotational axis; a plurality of circumferentially spaced electrical conductors affixed to the forward section of the bearing and spaced proximately to the circular current conducting element; a free end for transferring electrostatic energy to the circular current conducting element when the fixed electrical conductor is energized by a high voltage drop;
and an electrical conductor that facilitates contact charging of the liquid paint supplied to the first surface when the paint flows outwardly toward the atomization edge over the first surface in contact with the charging electrode. An electrostatic spray applicator for a rotary atomized liquid, consisting of: 2. first and second surfaces respectively affixed to the forward section of the bearing proximate the first and second surfaces;
a solvent spray nozzle for spraying a solvent to clean the surface; a solvent valve means mounted proximate to the forward section of the bearing; Claim 1, further comprising solvent conduit means coupled to a solvent nozzle for supplying solvent to the solvent nozzle to clean the first and second surfaces under the control of the solvent valve means. The device described in. 3. A rotary atomized liquid electrostatic spray applicator, comprising: a support made of an insulating material, the support comprising a front, middle, and rear section, the front section comprising a front surface; and a rotary atomizer made of an insulating material having an axis of rotation, the atomizer having a surface that allows liquid paint to flow outwardly against the atomizing edge when the atomizer is rotated about the axis of rotation. a rotary atomizer, the rotary atomizer being incorporated into the support and having means for charging the liquid application material; the rotary atomizer being drivably mounted on the front section of the support; drive means for rotating the device about the axis of rotation; means made of an insulating material for supplying liquid paint to the rotary atomizer when the atomizer is rotating about the axis of rotation; and the support. an annular ring removably attached to the front section of the bearing, the ring having a rear surface abutting the front surface of the front section of the bearing, and a front surface having a circular array of air passages; wherein the rear surface is a first
an annular inset, the inset communicating with and supplying air to the circular array of air passages to thereby form a circular array of air jets to shape the pattern of the atomized liquid paint; The rear surface of the annular ring further comprises an annular ring comprising a second annular inset, a circular conductor mounted within the second annular inset, and a plurality of circular conductors statically mounted in the annular air ring. circumferentially spaced electrical conductors, each having a rear end connected to the circular conductor and a forward free end spaced proximate to the rotary atomizer charging means; The front free end transfers electrostatic energy to the rotating atomizer when the stationary conductor is energized by a high voltage source connected to the circular conductor, so that the paint is transferred to the rotating atomizer. an electrically conductive material that facilitates charging of liquid paint applied to said rotating atomizer surface as it flows outwardly toward said atomizing edge so as to be in a charging relationship with respect to said rotating atomizer surface; An electrostatic spray application device for rotary atomized liquid consisting of: 4. A rotary atomized liquid electrostatic spray application apparatus comprising a generally cylindrical support having forward and aft sections disposed on opposite sides of an intermediate section, the intermediate section being disposed on opposite sides of the forward and aft sections; A rotary atomizer comprising an insulating material having a bearing having a diameter significantly smaller than that of the rear section and defining an annular cavity between these sections, and an axis of rotation, the atomizing device comprising: a rotary atomizer having a surface through which liquid paint can flow outwardly toward an atomizing edge of the atomizer when the device is rotated about said axis, and comprising means for charging the liquid application material; Drive means for rotating a rotary atomizer about its axis of rotation, comprising: a) an air turbine disposed within a cavity of said rear section bearing section; and b) a connection between said turbine and said rotary atomizer. and c) a bearing disposed within a cavity of the intermediate bearing section and rotatably supporting the shaft. drive means for supplying liquid paint to the surface of the rotary atomizer when the atomizer is rotating about its axis of rotation; and a) the annular cavity proximate the forward section of the support. b) a liquid application nozzle mounted in the forward bearing section proximate to the surface of the rotary atomizer; and c) the liquid application valve and the liquid application nozzle. Connect the
a liquid coating conduit for supplying liquid coating to the liquid coating nozzle under control of the liquid coating valve; further comprising: a conductor stationary in the forward bearing section; , a free end spaced closely to the circular conductive element, the stationary conductor transferring electrostatic energy to the conductive element when energized by a high voltage source to cause the paint to rotate in the rotation. The liquid supplied to said surface as it flows outwardly across said surface of said rotating atomizer in charging relationship with said charging means toward said atomizing edge under centrifugal force generated by rotation of the atomizer. An electrostatic spray applicator for rotary atomized liquid, which is comprised of a conductor that facilitates charging of paint. 5. a solvent application nozzle that is statically mounted on the front section of the front support close to the surface of the rotary atomizer and sprays the solvent to clean the surface; a solvent valve mounted in the annular cavity adjacent to the section; and further connecting the solvent valve and the solvent nozzle to supply solvent to the solvent nozzle under control of the solvent valve to supply the solvent to the rotary atomizer. 5. The apparatus of claim 4, further comprising solvent conduit means for cleaning said surface. 6. The apparatus of claim 5, wherein said solvent and liquid application valve is formed from a substantially insulating material. 7. A rotary atomized liquid electrostatic spray applicator comprising: a support; and a frust made of an insulating material supported by the support.
frnsto-) cone-shaped tubular rotary atomizer,
The atomizer cup has an inner surface and an outer surface extending between a rear edge and a front atomizing edge, the diameter of the front edge being larger than the diameter of the rear edge, and the atomizer having an axis of rotation. , means for supplying liquid application material to said atomizer cup to form a spray application pattern of application material; and electrostatic charging means for imparting an electrostatic charge to said application material; a cap having a generally convex outer surface along at least a portion thereof, the outer surface extending across the rotary atomizer as it rotates about the axis of rotation during normal operation; a cap configured to provide a generally laminar air flow; an air flow means disposed behind said atomizing edge to provide a generally forward flowing air flow; and further comprising: a cap configured to provide a generally laminar air flow; a repellent ring configured to be biased to the same polarity as the polarity of the charge, thereby causing the outer surface of the cap, the air flow means,
and a rotary atomized liquid electrostatic spray application apparatus, wherein the repellent ring cooperates to form the application pattern generally in front of the rotary atomizer. 8. The device of claim 7, wherein the cap further comprises a fitting, and the rotary atomizer is at least partially disposed within the fitting. 9. Claim 7, wherein the air flow means is constituted by: at least one air passage located behind the atomizing edge; and further means for supplying pressurized air to the air passage. The device described in. 10. The air passages are arranged in an array surrounding the rotary atomizer to form a corresponding array of air jets to shape and generally project the spray pattern forward. The device described in.