Caterpillar Tractor Co.

Other

Robert G Smead

Gary L Demeny

Thomas L Bagby

Thomas J Richards

Paul J Staebler

Stanley C Napadow

Charles E Lanchantin, Jr

A method of electrostatically painting and an apparatus for producing an electric field within a booth includes a paint spray gun charged to a first potential and a target to be painted to a second potential with one of the panels in the booth charged to a third potential intermediate the first potential and the second potential to repel paint particles away from the panel. The paint particles and the panels are charged to the same polarity and the target is of the opposite polarity. The panel is usually a wall, a ceiling and/or a conveyor protection housing within the paint spray booth. The preferred panel comprises an outer insulating layer of plastic, glass or porcelain that is easily wiped of paint and an interior, electrically-conducting layer such as a thin sheet of aluminum. Variations of the panel include a version which is completely enclosed in plastic and a version which is bonded to plastic.

Method and apparatus for repelling overspray in spray paint booths

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.

Method and apparatus for electrostatically spray painting objects in a

An electrostatic coating system includes a non-arcing electrical discharge zone having an approach section in which an elongated conductor connected to ground through a resistor converges towards the path of travel of a charge collector. The system also includes a contact section in which the conductor is adjacent the travel path of collector and the conductor physically contacts the collector as it passes through the contact section of the discharge zone. Conventional charge dissipation systems usually require separate resistors in each workpiece support member or a plurality of mechanically operated switches. The system initially inductively reduces the charge on the workpiece and then establishes electrical contact when a conductor connected to ground through a resistor is at about the same electrical potential as the workpiece and associated charge collector. The system is particularly useful in electrostatic coating systems having limited clearances which would prohibit the placement of a resistor in the workpiece support member.

Apparatus for removing an electrostatic charge from a charge collector

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.

Electrostatic spray gun

Electrodynamic painting system and method

A method of electrostatically coating an article (35) with paint includes projecting the paint from a gun nozzle (33) in a plurality of atomized particles, establishing an electric field (32) between an electrode (29) and the nozzle (33) sufficient for imparting an electric charge of one polarity to the particles at the nozzle (33), and establishing a zone of ions (80) in the pathway of the particles for neutralizing and reversing the polarity of a portion of the charged particles eminating from the nozzle (33). The plurality of diversely charged particles are attracted to the electrically charged article (35) along different individual paths in order to more uniformly paint irregular surfaces.

Method of electrostatically coating an article with paint

An electrostatic painting system has a charged conductor (22) extending along the path of travel of article carriers (11) through a coating zone (15, 16). A plenum (33) with a perforate wall (25) extends along the length of the charged conductor and is connected with a blower (30). A unidirectional flow of air is directed across the charged conductor.

Air flow system for the charging conductor in an electrostatic painting

A system and method for electrostatic coating of articles with paint particularly suited for coating irregular surfaces from a substantial distance. Water-borne conductive paint may be handled from an electrically grounded supply. Plural paint particle charging mechanisms are established by a DC potential applied to an electrode physically divorced from the paint stream. The articles being coated are electrically charged.

Electrostatic spray apparatus

An electrostatic coating system in which the workpiece to be coated is charged to a high DC potential. A conveyor moves the workpiece through a coating zone. A separate charge collector disc on the workpiece support passes close to but does not contact a charged conductor. An electrostatic charge is induced on the disc and is transferred to the workpiece. The conveyor is grounded and the workpiece support is connected to the conveyor through a high resistance which completes the charging circuit and drains the charge from the workpiece and support as they leave the coating zone. The ends of the charged conductor are curved away from the path of the charge collector. Insulating plates shield the conductor and limit swinging of the workpiece support.

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St. Charles, IL, United States of America

Robert G Smead