Abstract: An electrostatic spray gun apparatus includes a spray gun housing and a nozzle attached to a spray end of the housing, and a powder path that extends in a substantially straight line along an axis of the housing from the powder inlet to the powder outlet. The powder path is in the form of an enclosed smooth powder passage that is substantially continuous and uninterrupted from the powder inlet to the powder outlet to eliminate substantially all recesses or gaps that could capture or trap powder. The powder passage is formed by a plurality of tubular segments that are aligned along the housing axis and abut end to end, that when assembled in the housing axially compress the segments together to substantially eliminate dead spots or recesses to form the continuous smooth powder path. A gun purge function is provided that allows a purge line to be installed on the gun assembly. A cartridge valve and conductor assembly is provided between the gun electrode in the nozzle and the output of the voltage multiplier.

Abstract: A plurality of unconventional negative tribo-charging materials are described for use as the powder contact surfaces in tribocharging and corona powder spray guns, gun components, and powder delivery system components. The invention also provides a short barrel tribo-charging powder spray gun having an interchangeable powder contact insert and nozzle, with turbulence inducing air jets. The invention further provides novel tribocharging and corona gun designs. Improved powder coating systems are made possible wherein, for example, negative tribo guns can be utilized with negative corona guns to coat different parts of the same workpiece in a powder coating system.

Abstract: An electrostatic spray gun apparatus includes a spray gun housing and a nozzle attached to a spray end of the housing, and a powder path that extends in a substantially straight line along an axis of the housing from the powder inlet to the powder outlet. The powder path is in the form of an enclosed smooth powder passage that is substantially continuous and uninterrupted from the powder inlet to the powder outlet to eliminate substantially all recesses or gaps that could capture or trap powder. The powder passage is formed by a plurality of tubular segments that are aligned along the housing axis and abut end to end. that when assembled in the housing axially compress the segments together to substantially eliminate dead spots or recesses to form the continuous smooth powder path. A gun purge function is provided that allows a purge line to be installed on the gun assembly. A cartridge valve and conductor assembly is provided between the gun electrode in the nozzle and the output of the voltage multiplier.

Abstract: An improved apparatus for applying coating material includes a spray head having a housing which encloses a deflector. The deflector and housing cooperate to form a plurality of coating material flow channels which diverge in a direction of flow of coating material through the spray head. The deflector and housing cooperate to define a long thin outlet with relatively wide channel outlet sections at opposite ends of the outlet. An electrode assembly includes an electrode element having a long thin surface area which extends between opposite end portions of the long thin outlet and is exposed to the flow of coating material through the outlet. A wear tube encloses a portion of the electrode assembly and connects the deflector with the housing. The electrode element may be a plate which is molded into the deflector with a minor edge portion of the plate exposed to the flow of coating material.

Abstract: A mounting assembly for adjustably mounting a spray gun onto a mounting bar comprises a ball-and-socket joint attached at one end to the bar and attached at the other end to the gun, and an adjustment sleeve extending along the exterior of the bar. The sleeve is attached to the ball-and-socket joint and adapted to tighten the socket around the ball when the sleeve is turned to retain the gun securely in a desired position with respect to the bar. The mounting assembly allows for positioning the spray gun in an almost limitless range of possible orientations, and allows the securing mechanism to be easily tightened and loosened by the operator by turning the adjustment sleeve. An anti-back-ionization probe is attached to the gun and extends externally to the gun along the top or side of the gun. The probe comprising an elongated rod, which is easily removable and easily adjustable in length.

Abstract: An apparatus for use in directing a flow of air with particles entrained therein toward a workpiece includes a nozzle and a deflector. The nozzle has a passage with a noncircular cross sectional configuration. The deflector has an outer side surface with a circular cross sectional configuration. A flow of air with particles of powder entrained therein is conducted along outer surface areas on the deflector at a first volumetric flow rate. A flow of air with particles of powder entrained therein is conducted along outer surface areas on the deflector at a second volumetric flow rate which is greater than the first flow rate. The deflector includes a porous member which is releasably connected with a main portion of the deflector to facilitate cleaning and provide access to the interior of the deflector. Seal members are provided between an electrode sheet, the porous member, and the main portion of the deflector.

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: A tribo-electric powder spray gun includes a diffuser for mixing powder with a conveying gas, a charging portion downstream of the diffuser, and a sprayhead at the outlet of the charging portion for dispensing the charged powder. The charging portion has an inner core removably positioned within a hollow outer cylinder with an annular gap formed between the outer cylinder and inner core providing a charging flowpath for the powder. The inner core and the outer cylinder have undulating or wavy charging surfaces made of an electrically insulating material, so that the annular gap provides a tortuous path for the powder, enhancing powder contact and the charge imparted to the powder. Grounding is provided by surface conduction of the electrically insulating contact material through a ground ring located outside the powder path at the inlet to the charging portion of gun where the greatest amount of charging occurs.

Abstract: A hand-held powder spray gun includes a wand type handle that extends from the top of the handle and away from the rear of the gun, which provides for ergonomic operation of the gun. The wand handle can be converted to a pistol handle by removal of the handle from the gun body. The parts of the wand handle and the pistol handle are interchangeable to facilitate conversion and repair. The wand handle can be used with a diffuser having hose connections extending from the rear of the spray gun to make the gun easier to operate when held from above. A diffuser having hose connections at the bottom is also provided for use with a pistol type handle.

Abstract: A tribo-electric powder spray gun includes a diffuser for mixing powder with a conveying gas, a charging portion downstream of the diffuser, and a sprayhead at the outlet of the charging portion for dispensing the charged powder. The charging portion has an inner core removably positioned within a hollow outer cylinder with an annular gap formed between the outer cylinder and inner core providing a charging flowpath for the powder. The inner core and the outer cylinder have undulating or wavy charging surfaces made of an electrically insulating material, so that the annular gap provides a tortuous path for the powder, enhancing powder contact and the charge imparted to the powder. Grounding is provided by surface conduction of the electrically insulating contact material through a ground ring located outside the powder path at the inlet to the charging portion of gun where the greatest amount of charging occurs.

Abstract: A method and apparatus for spraying a solid particulate powder onto the interior surface of tubular articles by intermittently pumping the powder from a fluidized bed of powder through a powder supply line containing an intermittently operated venturi pump and air amplifier, as well as a pair of constantly operated air diffusers and an electrostatic charging apparatus. A powder collection shroud adjacent at least one open end of the tubular article has a carefully regulated vacuum applied thereto in order to collect oversprayed powders.

Abstract: A method for rendering uniform a coating applied to a substate is provided which redistributes a flowable non-uniformly applied coating with electrostatic forces after the coating has been deposited and before it solidifies. An electrostatic charging station charges the coating which, in the illustrated embodiment, is an insulative dip coating on a running length of rectangular conductive wire, as the wire emerges from a coating tank. The charged coating is passed to a coating redistribution station where shaped charged electrodes positioned to coincide with geometric high or low prints on the wire surface attract or repel coating material to cause it to flow from the more thickly to the more thinly coated regions. The redistributed coating is then dried at a drier station.

Abstract: A method and apparatus for spraying a solid particulate powder onto the interior surface of tubular articles by intermittently pumping the powder from a fluidized bed of powder through a powder supply line containing an intermittently operated venturi pump and air amplifier, as well as a pair of constantly operated air diffusers and an electrostatic charging apparatus. A powder collection shroud adjacent at least one open end of the tubular article has a carefully regulated vacuum applied thereto in order to collect oversprayed powders.

Abstract: Electrostatic liquid spray coating apparatus including a rotary atomizing cup of insulative material driven by an air turbine, is provided with a semi-conductive charging device extending through the cup, the inner portion of which is proximate the inner surface of the cup for contact charging liquid coating material supplied to the rear of the cup as it flows forwardly and outwardly over the rotating cup interior and contacts the charging device prior to atomization at the forward edge of the cup. A generally cylindrical insulative support body, housing a turbine and its associated air bearing and cup drive shaft, has a reduced diameter intermediate section which provides an annular cavity in which are located liquid coating and solvent valves for controlling the flow of liquid coating and solvent to the cup.

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.