Abstract: A rotary atomizing electrostatic coating apparatus having a rotating spray head, and a paint nozzle for feeding paint on the front surface of the spray head, in which the spray head is comprising a spray head main body made of an electrically insulating material, and a plurality of discharge electrodes having nearly band-form pattern extending outward approximately along the rear side shape of the spray head main body from the central side of the spray head main body with a mutual phase difference or extending symmetrically about the axis of rotation of the spray head main body. The plurality of discharge electrodes rotate together with the spray head main body, and the discharge current in the front side direction of the axis of rotation of the spray head is made uniform and increased, thereby enhancing the painting efficiency.

Abstract: A spray gun for applying powder to coat a work piece uses triboelectric and optionally a corona discharge electrode to charge powder particles electrostatically. The gun communicates with a source of pressurized air through a handle with an air valve controlling flow of the air. Powder in a container in fluid communication with the air flow is fluidized and entrained when the valve is opened. A nozzle with an internal surface defining a passageway to an open end communicates with the powder container. The internal surface of the nozzle frictionally imparts a net electrical charge of a first polarity to part of the powder by frictional contact during spraying. A plurality of discrete tubes are disposed in the central passageway and impart a net electrical charge of a second polarity to another part of the powder due to frictional contact as that part flows around and through the tubes.

Abstract: In a rotary atomizing head type coating machine, paint mist is prevented from depositing on a shaping air ring and synthetic resin cover. Shaping air ring includes an inner ring of a metallic material, an outer ring of an insulating synthetic resin material, and a shaping air outlet hole provided at the fore ends of the two rings. The inner ring has its base end electrically connected to an air motor, and provides an annular repulsion electrode at its fore end. This annular repulsion electrode induces strong positive discharges, thereby attracting clouds of negative ions, and preventing paint deposition on and contamination of the shaping air ring by a phenomenon of homopolar repulsions between clouds of negative ions and negatively charged paint particles.

Abstract: An electrostatic painting system for painting an object or article under corona discharge. The system comprises a spray gun which is formed at its tip end with annular air ejection opening through which air is ejected under pressure to atomize liquid paint ejected from a paint ejection opening formed at the tip end of the spray gun. An annular wire netting-like negative electrode is fixedly disposed at the tip end of the spray gun and located coaxially around the air ejection opening. The electrode functions to form an electrostatic field and a corona discharge field between the electrode and the object to be painted and to provide electric charge to the atomized paint, upon a high negative voltage being applied to the electrode.

Abstract: Induction charging apparatus for HVLP spray guns and air-assisted airless spray guns includes an air cap having a central orifice for receiving a spray gun nozzle. The cap includes one or more charging electrodes adjacent the orifice and carrying a voltage sufficiently large to induce on the spray droplets charges of a polarity opposite to that on the electrodes. A rotatable electrical connector enables the cap to rotate 360.degree. while maintaining electrical connections between the electrodes and a power supply. The spray gun nozzle is an airless nozzle receiving liquid at a pressure of about 1,000 psi and having a spray tip from which liquid is sprayed along a flow path coaxial with the electrodes. Air at less than about 10 psi is directed along the flow path to assist in the atomization of the liquid from the airless nozzle.

Abstract: A particle spray apparatus includes a spray gun having a deflector connected with a housing assembly. An electrode arrangement extends from the housing assembly into the deflector and is exposed to the flow of air with particles entrained therein to electrostatically charge the particles. The electrode arrangement is exposed to a flow of fluid to remove contaminants which may accumulate around components of the electrode arrangement. Accumulation of particles on an end surface of the deflector is discouraged by a flow of fluid from a chamber in the deflector through a porous member. The flow of fluid from the chamber is also conducted through a porous electrode sheet which extends along the porous member. Due to the relatively high voltage conducted through the electrode arrangement, an arc may tend to form in a passage along which fluid is conducted to the electrode arrangement. To prevent this from occurring, the passage through which fluid is conducted to the electrode arrangement is relatively long.

Abstract: An electrostatic powder-coating gun is provided which comprises a powder duct which is connected to a supply conduit for a powder-air-mixture and arranged along the longitudinal axis of the gun barrel and having an open mouth towards the work to be coated, a high-voltage generator, an electrode supporting tube extending through the powder duct in axial direction thereof, and a high-voltage electrode located on the supporting tube and protruding beyond the mouth of the powder duct towards the work. The high-voltage generator and the powder duct are disposed in series along the longitudinal axis of the powder tube in such a way that the powder duct is adjacent the muzzle of the gun barrel. The powder duct is comprised of a toroidal duct and an annular channel extending therefrom and opening to the outside.

Abstract: Induction charging apparatus for HVLP spray guns includes an air cap having a central fluid exit orifice for receiving the spray gun nozzle. The cap includes one or more charging electrodes surrounding the orifice and carrying a voltage sufficiently large to induce on the spray droplets charges of a polarity opposite to that on the electrodes. The cap includes a rotatable electrical connector to enable the cap to rotate 360.degree., while maintaining electrical connections between the electrodes and a power supply.

Abstract: A hand held electrostatic powdered paint spray gun that has a trigger which allows the user to vary the voltage and the paint density supplied to the gun. The trigger is coupled to a potentiometer that provides an output voltage to circuits that control the flowrate of the paint powder and a voltage supply to the paint powder.

Abstract: An electrostatic liquid coatings application process and apparatus is provided in which supercritical fluids, such as supercritical carbon dioxide fluid, are used to reduce to application consistency viscous coatings compositions to allow for their application as liquid sprays. The coatings compositions are sprayed by passing the composition under pressure through an orifice into the environment of the substrate. The liquid spray is electrically charged by applying a high electrical voltage relative to the substrate and electric current.

Abstract: In an electrostatic compressed air paint spray gun, the overall exit area of the compressed air discharge opening as well as the pressure and the quantity of the supplied compressed air are dimensioned such and matched such to one another that, first, the ratio (V.sub.L) of the air pressure (P.sub.1) prevailing immediately upstream of the compressed air discharge opening to the air pressure (P.sub.2) prevailing downstream of the compressed air discharge opening is less than 2:1 and, second, quantity and flow rate of the compressed air emerging from the compressed air discharge opening and magnitude of the applied high-voltage guarantee an adequate atomization of the paint as well as a conveying of the atomized paint particles to the workpiece with a given paint throughput and given paint viscosity. A high precipitation efficiency and a good paint compass are thus achieved.

Abstract: Easily replaceable pressure reducers are located at the front of the spray gun behind the air and fluid nozzles. These reducers are calibrated and marked for use with a particular air/fluid nozzle combination and maintain .ltoreq.10 psig exit air pressure. If the air/fluid nozzle combination is changed, the pressure reducers matched to the new combination are installed at the same time, illustratively using a screwdriver. By designing the air/fluid nozzle combination and pressure reducer as matched sets, the spray gun can always inexpensively be kept in compliance with any requirements under which an HVLP device must operate. "Fan-" or shaping-compressed air driven from the same compressed air which supplies the nozzle air is supplied through an additional pressure reducer valve to reduce its pressure below that of the nozzle air. The fan air reducer employs a drilled orifice of a calculated diameter. The atomizing air reducer is of a needle type that utilizes a controlling outside diameter.

Abstract: An electrostatic spray gun is provided with a spraying voltage control. The contol is produced by Hall effect or magnetoresistive circuitry incorporated with the circuitry of the spray gun. A variably positionable magnet is provided so that the operator may selectively adjust the spraying voltage by positioning the magnet relative to the Hall effect circuitry.

Abstract: A spray gun is provided with an angled spray head for use on painting robots. The spray head is designed for attachment to a conventional spray gun and utilizes an angled retaining ring in conjunction with a conventional retaining ring, a conventional spray cap, and angled fluid nozzle. This arrangement allows rotation and orientation of the pattern at various angles relative to the body of the robot as desired by the operator. The electrode needle is formed of flexible material so as to enable it to flex through the angled fluid passage.

Abstract: An adapter for converting spray guns to electrostatic or induction charging includes a housing mountable on a spray gun. A high voltage power source is contained in the housing and is connected to an electrode assembly mounted on the front of the housing. The electrode assembly includes four electrodes which extend in front of the spray gun nozzle and air cap and are spaced symmetrically around the spray axis. The nozzle is electrically grounded, while the electrodes carry a voltage in the range of 3-15 kV, to produce in the spray path from the nozzle an electrostatic field which produces electrical charges on the sprayed particles. When conductive liquids are sprayed, the particles are charged by induction at relatively low electrostatic field gradients, while nonconductive liquids require high electrostatic field gradients which produce corona effects. These corona effects are enhanced by the provision of a corona needle mounted on the nozzle at the spray axis.

Abstract: An electrostatic spray gun particularly adapted to the spraying of fast-drying paint mixtures while preventing the polymerization or setting up of the paint mixtures includes a gun body having defined therein a gun inlet for receiving paint, a gun spray orifice, an annular seat surrounding the orifice, and a supply passage communicating the gun inlet and the orifice. The gun also includes a valve assembly including a reciprocable valve member engageable with the valve seat to close the orifice and define a closed position of the valve member. The valve assembly further includes an electrode extending from the valve member through the orifice.

Abstract: Improved apparatus for indirectly charging atomized electrically conductive fluids discharged from a spray gun. One or more high voltage electrodes are located outside of the atomized fluid envelope for imparting a charge to the fluid droplets. Air curtains are established to surround insulated electrode holders for preventing a buildup of electrically conductive deposits on the holders. The air curtain is strongest at the end of the holder closest to the atomized paint envelope. The electrodes may be supported from an adapter which permits retrofitting on existing direct charge electrostatic spray guns.

Abstract: A hand held spray gun including a gun body, a barrel and a nozzle assembly attached to the front of the barrel. A tubular retainer passes through a portion of the body and is threaded into a passage in the barrel to connect the barrel to the body. A fluid valve actuator extends from the body through the retainer and into the barrel passage for operating a fluid valve in the nozzle assembly. The retainer also functions as a guide for the valve actuator, holds a radial fluid seal for forming a sliding seal against the valve actuator and serves as a stop for a spring biased fluid seal between the valve actuator and the barrel.

Abstract: A hand held electrostatic spray gun having an electrostatic power supply mounted in the gun. The power supply includes a circuit module mounted in the gun handle which produces heat during operation. The circuit module has a heat conducting housing which is intimately attached to a heat conducting tube extending through the handle. Compressed air delivered through the tube to a nozzle for assisting atomization and/or pattern shaping cools the circuit module.

Abstract: A continuous electrical connection between a high voltage power source and a paint charging electrode in an electrostatic spray gun. The electrode is mounted on a valve needle which is reciprocated by a trigger mechanism as the spray gun is operated. A novel spring establishes and maintains the electrical connection from a stationary contact on the gun barrel to the moving valve needle. The spring may be mounted on a spacer tube mounted coaxially about the valve needle. The spacer tube can move in an axial direction to exert a force on a seal between the barrel and the valve needle without affecting the electrical connection.

Abstract: An electrostatic spraying apparatus in which an electrode is mounted adjacent to the sprayhead, means are provided for causing a first electrical potential to be applied to liquid emerging from the sprayhead, and further means are provided for applying a second electrical potential to the electrode. The difference between the first and second potentials is sufficient to cause an intense field to be developed between the emerging liquid and the electrode, sufficient to atomise the liquid. The electrode has a core of conducting or semiconducting material sheathed in a "semi-insulating" material. This "semi-insulating" material has a dielectric strength and volume resistivity sufficiently high to prevent sparking between the electrode and the sprayhead and a volume resistivity sufficiently low to allow charge collected on the surface of the material to be conducted through the "semi-insulating" material to the conducting or semiconducting core.

Abstract: A flat spray nozzle for a powder spray gun comprises a nozzle body formed with an axial powder flow passageway, a pair of spaced powder discharge slots intersecting the powder flow passageway and a bore located between the powder discharge slots. The bore in the nozzle body receives an electrode which extends forwardly of the spray nozzle, between the powder discharge slots for electrostatically charging particulate powder material emitted from the powder discharge slots without disrupting the spray pattern of particulate powder material.

Abstract: An electrostatic powder spray gun comprises a powder channel for a powder-air mixture to be sprayed, the powder channel extending through a pistol tube and discharging axially forward at the forward end of the gun through an annular opening which is coaxial with the longitudinal axis of the pistol tube. An auxiliary air line extends through the pistol tube and discharges at the forward end and is constructed in such a manner that the auxiliary air line discharges axially forward as an annular opening coaxial with the annular powder opening, in particular radially and slightly in front of the annular powder opening. An air deflecting member is arranged in front of the auxiliary air annular opening and is seated at the free end of a rod which extends centrally through the pistol tube and is axially displaceable therein. The rod is mechanically coupled to the trigger of the spray gun so that the air deflecting member can be adjusted from the trigger.

Abstract: An air atomizing electrostatic coating gun which atomizers a liquid paint by using air flows and thereafter applying atomized liquid paint to an object to be coated by using an electrostatic force. In this coating gun, all of a rod valve, a driving piston, an air cylinder and valve support members of a needle valve device are made of insulating materials having good insulating properties, and an electrode for charging paint particles is attached to the valve. A nozzle-needle valve assembly which is integrally constructed by attaching a paint nozzle to a cylindrical extension of the air cylinder which is formed at a front end portion thereof, is inserted and fitted into a generally cylindrical cavity in a front end portion of the gun body from the front side thereof.

Abstract: An electrostatic particle spray gun having, in one preferred embodiment, a conical deflector of insulative material mounted in the nozzle in the particle path for forming a conical particle spray pattern. A resistive sheet connected to a high voltage electrostatic supply is sandwiched between the forward and rearward ends of the deflector, leaving only the perimeter of the sheet exposed at the peripheral region of the conical deflector. The perimeter of the resistive sheet functions as a multi-point circular electrode for charging the particles such that improved coating transfer efficiencies are achieved. Also, because of the resistive nature of the resistive sheet, the sheet constitutes a resistor in the electrical current path between the center of the sheet where it connects to a high voltage terminal and the circular periphery of the sheet which serves as the multiple point charging electrode, thereby minimizing unsafe electrical discharges should the electrode inadvertently approach a grounded object.

Abstract: An apparatus and process for the electrostatic spraying of a mixture of a plurality of liquids, suitably liquids which react together rapidly to form a solid, liquids which are physically imcompatible, or liquids, such as paints, to provide novel optical effects. The apparatus includes a sprayhead formed with a plurality of channels which communicate with a common outlet means. The liquids are supplied to respective channels and meet at the outlet means. There they are subjected to an electrical field which causes a mixture of the liquids to be drawn from the sprayhead in the form of one or more filaments, the or each filament constaining a mixture of liquids in the proportions equal or substantially equal to the proportions in which the liquids were supplied to the sprayhead.

Abstract: A gun head constituting the front section of an electrostatic powder painting gun makes the pattern of powder flow spouted out therefrom into the form of a flat fan-like shape to decrease the velocity of the powder flow traveling toward a workpiece to be painted to thereby enhance the efficiency of adhesion of the powder paint to the workpiece. A spout section of an end wall of a cylindrical body constituting a fundamental section of the gun head has a pair of opposed slits bored therein such that the spacing between these slits decreases progressively as approaching the outer ends thereof, and the inner ends of these slits communicate with a powder path formed inside the cylindrical body at opposed spots close to the inner surface of the powder path.

Abstract: An electrostatic spray device and cable assembly for charging coating material applied to an article in industrial finishing operations includes a gun body having a powder flow passageway and a dielectric sleeve contained within the passageway such that the discharge opening of the spray device surrounds the sleeve. The cable assembly comprises a dielectric tube having a hollow interior and a high voltage electrostatic cable mounted within the tube and connected at one end to a supply of electrostatic voltage. A particle deflector having an electrode in the form of a resistive sheet is mounted by the tube in charging relationship to a coating particle discharge opening in the spray gun, and the opposed end of the cable is electrically connected to the electrode. An adjustment device acts on the tube and cable to move them as a unit within the passageway in the spray gun to adjust the axial position of the deflector and electrode relative to the particle discharge opening in the spray device.

Abstract: It is described a novel powder charging apparatus, wherein a high voltage is applied between a couple of electrodes, consisting of a plasma electrode of required polarity and a plasma electrode of opposite polarity, to form plasma at tip of each of electrodes, an eventually finely dispersed powder is made to pass only through an area wherein mainly ones of negative and positive ions derived of said plasma, that is, ions of required polarity exist, and thereafter the charged powder is discharged. In this apparatus, the adhesion of powder to each electrode is prevented and charging performance is maintained for a long time. It is also described an electrostatic powder coating apparatus comprising the above-described novel powder charging apparatus, which is excellent in performance for making thick coating, depositing efficiency and throwing power.

Abstract: A portable electrostatic spray gun for liquid and/or pulverulent materials has a body with a grip and a second portion which carries a detachable barrel and has an inlet for admission of material to be sprayed. The rear side of the grip has a socket for a first unit of the high-voltage generator. A second unit of the generator is installed in a chamber provided in the second portion of the body and being accessible upon separation of the second portion from the grip. The grip contains a proximity switch which is actuatable by the trigger and can be deactivated by rotating it in the grip. The first unit of the generator has a transformer and an oscillator connected to a low-voltage input, and the second unit has a voltage multiplier connected with two high-voltage electrodes, one in the inlet and the other in an air admitting channel which is provided in the second portion of the body and includes a passage in the second unit of the generator.

Abstract: A versatile spraying gun includes main tool and several attachment tools any one of which can be inserted in the main tool. Each attachment tool is designed to atomize powder particles that are to be sprayed on an article in accordance with a specific spraying method and atomization principle and method. The main common tool is comprised primarily of a body that defines a powder delivery channel and a coupling piece and discharge electrode located upstream in the delivery channel. The attachment tools have a flow guide member disposed axially within the delivery channel and an attachment piece for attaching the attachment tool to the coupling piece of the main tool. In some attachment tools, the flow guide member also houses a high voltage circuit and appropriate electrodes needed for electrostatic charging of the powder which passes through an electrical field set up between the electrodes.

Abstract: A lance extension venturi sleeve is disposed preferably within the rear one-third of the lance extension of a powder spray gun. The sleeve increases the velocity of the powder stream and provides an abrupt opening to the larger lance extension tube. The velocity increase and the turbulence so created increase the homogeneity of the powder in the stream and produce a more uniform powder spray pattern or powder "cloud" for even powder coating of articles to be coated.

Abstract: An atomized cloud of droplets having an electric charge is generated wherein different discrete parts of the cloud are formed from different liquids. The discrete part of the cloud which has an active ingredient, such as a chemical insecticide or herbicide, is contained such as by enveloping it or directing it in a particular direction by a further discrete part of the cloud that includes an inert liquid such as water. The spraying apparatus comprises a plurality of nozzles positioned in a high velocity air stream to disperse liquid and generate an atomized cloud of the liquid. The nozzles are grouped into at least two sets, each set being arranged and positioned to generate a discrete part of the cloud. An electric charge is placed on the droplets as they are emitted. Each set of nozzles further include a liquid reservoir connected to the nozzles. Each reservoir is to contain a different liquid whether it be an inert liquid or different concentrations of an active liquid.

Abstract: Electrostatic painting apparatus comprises a support moveable at high speed along a slide. On this support is a pneumatically controlled paint sprayer producing an electrostatically charged jet of paint. A paint feed assembly comprising a pressure regulator and a discharge valve is juxatposed with the sprayer. Sprayer control devices are disposed on a chassis connected to the feed assembly by a harness. These control means comprise three gas pressure regulators supplying the sprayer and controlling the paint pressure regulator and a high DC voltage generator. The position of the chassis relative to the slide is determined such that the harness is as short as possible, so as to reduce to a minimum the command transmission time. This arrangement makes it possible to reduce the weight carried by the support. The units carried by the chassis are remotely controlled by a microprocessor-based unit over a remote control line.

Abstract: An electrostatic paint spray gun comprises a needle-shaped electrode centrally seated in the paint channel which supplies paint to a spray nozzle and projects slightly beyond the spray nozzle. The electrode is composed of two needle electrodes disposed coaxially behind one another and electrically connected in series. The rear needle electrode is secured to the pistol tube and the forward needle is secured to a closure containing the spray nozzle and emplaced on the pistol tube of the spray gun. When the closure is in place, the rear electrode needle represents the electrical connection to the forward electrode needle, whereas, when the closure is removed, the tip of the rear electrode needle projects freely beyond the mouth of the pistol tube.

Abstract: An adjustable pattern powder spray nozzle assembly comprising a nozzle body having an axial powder flow passage extending therethrough and a pair of rotatable adjacent shafts extending across the powder flow passage. The shafts are in contact with each other substantially along their length and each has a slot formed in the periphery thereof. The slots are oppositely positioned so as to define a powder flow opening therebetween. The shafts are interconnected by gears at the ends thereof so that they are rotatable in unison to vary the configuration of the opening and thereby, the pattern of powder sprayed from the nozzle assembly.

Abstract: A powder spray gun for spraying solid particulate powder material wherein there is a venturi sleeve mounted internally of the gun barrel, within the rear of an extension tube, for increasing the velocity of powder conveyed therethrough and for generating turbulence in the powder so as to better dispense the powder throughout the powder pattern emitted from the gun.

Abstract: An electrostatic spray gun for spraying solid particulate powder materials while entrained in a gas medium, including an electrically non-conductive housing having an electrode extending forwardly therefrom and a straight electrically non-conductive powder transport tube adjustably and replaceably mounted within the housing so as to enable the discharge end of the tube to be positionably adjusted relative to the electrode or to be replaced with a tube of differing internal diameter so as to vary the transport velocity at which the powder is emitted from the discharge end of the tube.

Abstract: A powder spray gun which, in the presently preferred embodiment, is particularly adapted for spraying a particulate powder spray onto the interior surfaces of containers and other target objects in a confined area. The apparatus includes a rigid tubular support member and a flexible powder transport tube. The rigid support member carries a high voltage cable having a charging electrode at one end. The flexible tube terminates in a discharge nozzle which may be adjustably mounted to the support member adjacent the charging electrode so as to permit variation of the angle at which the powder is released from the nozzle relative to the longitudinal axis of the support member. Intermediate the discharge nozzle and an upstream portion of the powder transport tube which is connected to the support member, the flexible tube is smoothly curved so as to prevent any sharp corners in the transport tube or the nozzle within which powder could collect and interrupt smooth, even discharge of powder from the gun.

Abstract: The invention relates to a device for the powder-dusting of moving objects, particularly flat substrates in the form of webs and sheets of paper, plastic or textile with a nozzle housing made of electrically insulating material, with at least one nozzle provided on the housing for releasing a powder air stream laden with dusting powder and with metallic electrodes and counter-electrodes disposed on the housing for producing an electrical high-voltage field. To obtain a powder air stream with powder particles as neutral as possible, it is envisaged that at least one electrode and a counter-electrode cooperating with the latter are disposed on the outside of the housing in the vicinity of the nozzle whereby an electrical high AC voltage is applied to the electrode and counter-electrode, whereby, after being released from the nozzle, the powder air stream penetrates the thus produced high AC voltage field on the outside of the housing.

Abstract: A tool for removing the nozzle assembly of a coating spray gun. The tool has an inner wall surface of a configuration congruent with an outer surface of the spray assembly. The inner wall thereof defines a cavity which is closed at one end thereof such that the tool, when placed over the nozzle assembly, encloses the nozzle and protects the user from spray injection. Preferably, the outer surface of the tool is knurled to facilitate use.

Abstract: An electrostatic spray gun muzzle comprises an insulating tube having a rear end adapted to be mounted in an electrostatic spray gun and a front end providing an exit for charged coating material. A conductive rod is mounted axially within the tube and has a conductive pin extending radially from one end thereof. The pin is electrically connected to a power terminal when the rear end of the insulated tube is mounted in a spray gun. A plurality of conductive centering bars extend radially from the rod, adjacent the front end of the insulating tube, to maintain the rod in centered, axial alignment with the insulating tube. An insulating deflector is mounted to the conductive rod, forward of the front end of the insulating tube.

Abstract: Apparatus is disclosed for spraying electrostatically charged particles of paint toward a workpiece. Increased paint throughput is achieved over prior art devices by employing enlarged paint discharge passages and two different air streams. One air stream, which is adjustable in flow, serves to atomize the paint into substantially uniform, very tiny droplets and the other air stream, which is also adjustable in flow, directs the atomized paint toward the workpiece. Safety is increased by positioning the paint charging electrode within a paint delivery passage located relatively far upstream from the paint nozzle. A second electrode in the nozzle is "floating" in electrical potential and serves to supply additional electrical charge to the very fine paint particles as they issue from the nozzle. In this manner, the impedance of the paint itself and the "floating" electrode serve to reduce the risk of sparking between the paint spraying apparatus and the workpiece.

Abstract: A plastics material covered metal electrode maintains an electrostatic field dissipating the particles of fine dry powdered dielectric material such as flour or starch to create a cloud or dry mist of the powder in the path of freshly inked sheets as they are discharged from a printing press to prevent smudging of the ink and sticking together of the successive sheets as they are stacked. The electrostatic field is formed across the path of the powder as it is discharged from a supply trough by energizing the electrode with a high voltage current. The plastic covered electrode replaces heretofore required neon gas filled glass tubes which are fragile and burn out. The preferred plastic covering for the electrode is a thermoplastic polyetherimide resin marketed under the name of "Ultem" by General Electric Company of Pittsfield, Mass.

Abstract: Electrostatic spray coating system wherein the output voltage is maintained constant over the working range of the system and wherein the power is automatically interrupted whenever the load current exceeds a predetermined amount, as for example, about 120 microamperes.

Abstract: An electrostatic spray gun (10) for the spray application of electrically conductive materials includes a shield (24) to prevent the build-up of electrically conductive flash deposits on preselected non-conductive surface areas (26) of the gun (10). By prohibiting the build-up of electrically conductive flash on preselected areas of the gun surface, the shield (24) is effective in preventing the completion of an electrical circuit between a charged electrode (18) and an electrically grounded gun support member (22). The gun of the present invention is particularly effective in the high volume spray deposition of electrically conductive paints.

Abstract: An air atomizing nozzle assembly for electrostatic spray guns is disclosed. The nozzle assembly is made of plastic parts and includes an air cap having a central bore which surrounds a fluid nozzle tip. The nozzle has a nut formed on its forward end to facilitate threading of the rearward end of the nozzle tip into a threaded bore of the gun body. Formed on the front part of the nozzle, either as a part of the nut or a cylindrical surface adjacent the nut, is an accurately machined surface engageable in press fit relationship with a mating accurately machined bore of the air cap. These mating press fit surfaces center the bore of the air cap relative to the nozzle tip so as to leave an annular, evenly dimensioned air flow passage surrounding the nozzle tip and defined between the nozzle tip and the bore of the air cap. The air cap is retained in a one-piece resilient retaining ring by snapping the air cap into an annular lip of the retaining ring.

Abstract: An electrostatic spray gun having a rotatable voltage generator for providing electrical energy at low voltage for conversion within the spray gun into electrostatic high voltage energy, wherein a rotating voltage generator is driven by an air turbine under the influence of a pressurized input air supply, the pressurized air passing through conduits in the handle of the spray gun, an air valve actuated by a trigger, an air flow regulator, and into impinging contact against rotatable turbine blades. The air supply is exhausted from the spray gun through internal passages which provide cooling air to the electrical components within the spray gun, and through further passages opening from the bottom of the spray gun handle which minimize the audible noise caused by such air flow.

Abstract: An air atomizing nozzle assembly for spray coating systems such as an electrostatic spray gun is disclosed. The nozzle assembly includes an air cap having a central bore which surrounds a fluid tip nozzle. The bore has a plurality of uniformly dimensioned axially aligned gas flow passages evenly spaced about its circumference and a plurality of radially inwardly extending ribs therebetween. The ribs engage the outside surface of the fluid tip nozzle to positively align its center axis on the axis of the central bore. The air cap and nozzle tip thus cooperate to form a plurality of uniform gas flow passages around the nozzle thereby producing a finely atomized uniform spray pattern of coating material emitted from the fluid tip. In a preferred embodiment of the invention, the gas flow passages and ribs are formed in a metal element inserted in a center bore in the air cap. The metal element is so dimensioned that the ribs make a press fit with the fluid tip to positively align it.

Abstract: A powder spray gun which, in the presently preferred embodiment, is particularly adapted for spraying a particular powder spray onto the interior surfaces of containers and other target objects in a confined area. The apparatus includes a rigid tubular support member and a flexible powder transport tube. The rigid support member carries a high voltage cable having a charging electrode at one end. The flexible tube terminates in a discharge nozzle which may be adjustably mounted to the support member adjacent the charging electrode so as to permit variation of the angle at which the powder is released from the nozzle relative to the longitudinal axis of the support member. Intermediate the discharge nozzle and an upstream portion of the powder transport tube which is connected to the support member, the flexible tube is smoothly curved so as to prevent any sharp corners in the transport tube or the nozzle within which powder could collect and interrupt smooth, even discharge of powder from the gun.