Abstract:
The present invention provides an apparatus for controlling the spray of positively-charged coating particles towards a grounded or negatively-charged dielectric material having a dielectric constant less than 4.0 and in the form of a hollow container. This apparatus includes: (a) a device for inducing a positive charge onto a coating composition, (b) a device for creating a field of positively-charged coating particles, (c) a device for supporting a series of hollow containers in spaced relation to one another which includes a series of vertically-oriented spindles, (d) a device for transporting the spindles in series through the field of positively-charged coating particles, (e) a gripping chuck made from, or coated with, a dielectric material, or both, mounted to the upper end of a spindle, the chuck having a recess defined therein for receiving the opening of a hollow container, and (f) a grounding device positioned such that, when the dielectric container is in the path of the sprayed, positively-charged coating particles the grounding device is also in the path but shielded therefrom by the dielectric material. The grounding device is insulated from direct electrical contact with the supported container. The grounding device can be replaced by an internal charging device for inducing a negative charge onto a hollow container being supported by the gripping chuck. Moreover, the grounding device or the internal charging device can be used in conjunction with an external charging device for inducing a negative charge onto a hollow container being supported by the gripping chuck.
Abstract:
This invention provides a process for electrostatically applying a coating composition onto dielectric materials which have a dielectric constant less than 4.0. In this process, a positive charge is induced onto a coating composition. The dielectric material is electrically isolated, negatively charge, or both. The positively-charged coating composition is sprayed onto the dielectric material. If the dielectric material is charged negatively, the process of the present invention further includes the step of maintaining at least a portion of the negative charge on the dielectric material while positively-charged coating particles are being sprayed thereon.
Abstract:
An electrostatic spray apparatus, including a spray hood having an electrode. The hood defines a top region with a depending skirt and comprises first and second hood elements, either or both of which may comprise molded shells, with an electrode sandwiched therebetween. The electrode extends over the top region and down the skirt and terminates short of the lower regions of the skirt. The hood is constructed such that, other than at the lowermost regions of the skirt, the hood does not have any junction of its planar surfaces having a radius less than one hundred and fifty millimeters. The hood has an opening in its top region, through which an electrostatic spray head is placed into the hood. The electrode presents a connection for an electrical supply, and the potential applied to the spray head is substantially the same as that applied to the electrode.
Abstract:
A spray painting booth for electrostatically painting objects includes encapsulated electrically charged panels which are adapted to repel electrically charged paint particles that are produced by an electrostatic spray painting device. The electrostatic spray painting device is charged to a potential of 60,000 to 135,000 volts DC negative with respect to ground so that the resulting spray of paint particles is negatively charged. An object or article to be painted is disposed in the booth by a conveyor mechanism and is maintained at ground potential. The encapsulated, electrically charged panels or walls of the booth are charged to a potential of 30,000 volts DC negative with respect to ground by a power supply such that the panels are charged to a potential between the negative DC potential with respect to ground to which the spray paint device is charged and the ground potential of the article to be painted. The resulting electrostatic field emanating from the panels repels paint particles that do not adhere to the article and thereby reduces the amount of paint that would otherwise accumulate on surfaces of the spray paint booth near the article being painted.
Abstract:
A cover for forming a space for coating is provided above an electroconductive belt conveyor for adjusting an electric field at an end portion of a flat plate-like object to be coated, electrostatic powder coating guns pointed at the object to be coated on the belt conveyor in the space for coating are provided, and means for introducing air into the space for coating and means for exhausting the air are respectively provided. As a result, the strength of the electric field formed from the electrostatic powder coating guns to the electroconductive belt conveyor and the object to be coated is made uniform through their entire surface so that the thickness of a powder layer to be adhered to the object to be coated is made uniform from its central portion to an end portion. Consequently, the waste of the powder coating material is prevented, and local cracks in a portion having a great thickness generated when the coated object is bent are prevented.
Abstract:
Apparatus for spray coating plate-like or otherwise configurated workpieces has an endless apertured conveyor which transports a series of workpieces along a horizontal path beneath a rotary atomizer which sprays coating material onto the advancing workpieces. The coating material which bypasses the workpices and passes through the apertures of the conveyor impinges upon and gathers on a web of paper or non-woven fibrous material which is advanced at a speed less than the speed of the conveyor so that the web can be used with great economy because it is or can be advanced at a rate such that, or only when, its portion which is in the path of sprayed coating material cannot gather and retain additional coating material.
Abstract:
Electrostatic spraying apparatus and process for spraying liquids which form a coalescent resistant surface in flight in a particular environment to produce a powder or granular material. The process involves delivering a liquid to a spraying site of an electrostatic spray head; making contact with the liquid via an electrically conducting or semiconducting liquid contacting surface; charging the liquid contacting surface to a high voltage of one polarity relative to a reference surface to intensify the electric field strength at the spraying site sufficiently that the liquid at the spraying site is drawn out preponderantly by electrostatic forces into at least one cone from which a corresponding ligament issues and breaks up into a spray of electrostatically charged droplets; providing the environment in a space sufficient that droplets from the spray head form, in flight, particles having a substantially coalescent resistant surface; and collecting the particles so formed.
Abstract:
An electrostatic system analyzer for checking the voltage at various test points in a high voltage electrostatic spray coating system. The analyzer is in the form of a gun having a telescoping cylindrical barrel with an exposed electrode at its forward end, and a meter at its rearward end, and having a downwardly extending conductive handle. The forward portion of the analyzer body, which is axially and angularly movable relative to the rearward portion, includes a conductive receptacle electrically connected to the electrode, and the rearward, portion of the analyzer body includes four axial bores equidistant from a central axis and equiangularly arrayed thereabout. Each bore contains a resistor, and the resistors are electrically connected in series, with three of the resistors each having an individual plug extending toward the forward analyzer body portion and being receivable for electrical contact within the receptacle when the two portions are telescoped together. The particular resistor coupled to the electrode through the receptacle and its associated plug is determined so as to introduce sufficient resistance from the series of resistors to compensate for resistance variations at different test points in the electrostatic system.
Abstract:
AN APPARATUS AND A METHOD FOR DEPOSITING CHARGED PARTICLES OF A POWDERY SUBSTANCE ONTO AN EDGE OF A SUBSTRATE. THE APPARATUS MAY INCLUDE MEANS FOR EMITTING PARTICLES OF A POWDERY SUBSTANCE TOWARD THE SUBSTRATE. SUBSTANTIALLY ALL OF THE PARTICLES ARE PROPELLED BEYOND A LEADING EDGE OF THE SUBSTRATE TO THE VINCINITY OF A TRAILING EDGE OF THE SUBSTRATE. ANOTHER MEANS IS ADJACENT THE TRAILING EDGE OF THE SUBSTRATE WHICH IS CAPABLE OF CAUSING ELECTROSTATIC DEPOSITION OF THE PARTICLES ONTO THE TRAILING EDGE OF THE SUBSTRATE.