Onoda Cement Co., Ltd.

Kenji Ouchi

Takeo Shimizu

Tsutomu Itoh

Nobuo Furuya

Hiroshi Saitoh

A workpiece which may be made of a highly electrically insulating material is held in a spaced opposing relationship with respect to a silent discharge plate electrode to which an a.c. voltage is applied. A d.c. voltage is applied across the workpiece and the silent discharge plate electrode to form a driving electric field therebetween. Powder particles suspended in air are charged in the same polarity as that of the silent discharge plate electrode and then injected into the region between the silent discharge plate electrode and the workpiece where the electric field drives the charged particles toward the workpiece to coat it. The a.c. voltage is sufficient to repel the electrode surface confronting the workpiece and to maintain the silent discharge at a reduced level and effectively precluding deposit of powder particles on the mentioned surface. An apparatus for the electrostatic coating is also disclosed.

Method and apparatus for electrostatic powder coating

This invention relates to a continuous process for electrostatically coating a substantially axially symmetrical object with pulverized material, characterized by conveying said object by means of a conveyor-type holding device into an electrostatic coating chamber equipped with silent discharge plate electrodes on both sides of the chamber walls: feeding electrically charged pulverized material into said chamber: electrostatically coating said object with said pulverized material by the action of silent discharge from said electrodes: and removing surplus pulverized material from the specific parts of said object by suction. This invention further relates to an apparatus used for continuously electrostatically coating a substantially axially symmetrical object with pulverized synthetic resin, characterized by comprising (i) an electrostatic coating chamber where said pulverized synthetic resin is coated on the surface of said object maintained at a temperature below the melting point of said resin, which object has been conveyed into said chamber by means of a holding device and (ii) a device for removing surplus pulverized resin from the specific parts of said object by suction in order to electrostatically coat the desired part only.

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Chiba, Japan

Kenji Ouchi