Abstract:
An electrostatic powder spraying apparatus that includes a nonrotating disk-like member having an edge; the electrostatic field extends between the edge of disk and articles to be coated. A first means of the apparatus deflects powder radially outwardly into a chamber. The chamber is adjacent the first means and provides space in which tangential streams impart a spiral motion or whirling cyclone-type motion to the radially deflected powder. An apertured means is spaced from the non-rotating disk-like member. The spiral motion of entrained powder moves it outwardly along the surface of the non-rotating disk-like member and causes air to be aspirated through the aperture to mix with the powder moving radially outwardly along the surface of the disk-like member. By this means the powder is given sufficient momentum to be ejected from the edge of the disk to the vicinity of an article at a powder attracting potential where the electrostatic field forces can guide the charged powder to the article.
Abstract:
This invention is directed to a pneumatic flow switching device particularly adapted for the electrostatic coating of tubular workpieces, particularly can bodies, and includes a generally cylindrical chamber, a conduit for peripherally delivering a fluidized admixture of powder and air into the chamber, means for peripherally exhausting the powder-air admixture from the chamber, means adjacent the conduit for directing air tangentially into the chamber whereby the powder-air admixture is directed toward the exhausting means, and means for pneumatically traversing the powder-air admixture generally axially of the chamber for the delivery to an article intended to be treated thereby.
Abstract:
Disclosure is made of an apparatus for the application of powdered materials onto an article in an electrostatic field, said apparatus having an electrically insulating housing communicating with a bin, said housing having a rotary screw conveyor disposed inside it, said screw conveyor being made of a dielectric material; said screw conveyor and the housing make up a channel for the supply of a powdered material from the bin to a pulverizer electrode made in the form of two coaxial cylindrical sleeves, one of said cylindrical sleeves being rigidly secured at the outlet end of the housing and having on its inner surface acicular pins arranged radially and pointing with their sharp ends toward an article being coated, whereas the other sleeve is disposed at the outlet end of the screw conveyor and is also provided with acicular pins arranged along the perimeter of the end face of the cylindrical sleeve, parallel to the screw conveyor axis, the sharp ends of said acicular pins pointing toward the article being coated; both said cylindrical sleeves are under an equal electric potential.
Abstract:
Method for applying coating materials to articles, using electrogasdynamic apparatus providing a flow channel having a dielectric boundary which has a length/width ratio of greater than 2.5. Gas containing particulate coating material is ionized to create an electrical discharge field for imparting an electrical charge to the particles prior to passage through the dielectrically bounded flow path and thereby creating a high space charge potential. In special applications, a free-radical forming monomer gas or a fusible particle substance is carried in an inert gas into the electrical discharge field and through the flow channel toward the article to be coated. In any case, the charged particles are subjected to an axial charge repelling field (due to space charge effects) in the flow channel to raise the electrical potential of the particles, and thereby the potential gradient between the particles and the workpiece.
Abstract:
The powder spray gun comprises a handle, a barrel and a front member screwed to the barrel. The barrel and the front member form a duct through which paint powder is conveyed entrained in the air. An annular electrode and an elongated central body are clamped between the barrel and the front member and a lead for high voltage extends through an axial bore in the barrel and abuts axially against the annular electrode. The duct is annular and the electrode has an annular forward-directed edge that has a clearance to the walls of the duct and is located at a touch protecting distance from the mouth of the duct.
Abstract:
An improved control device for apparatus for coating articles with an electrostatically charged material in discrete form. The apparatus includes a nozzle having an inlet and a discharge outlet for the particulate material, an electrode for electrostatically charging the particulate material and at least one passage for directing a stream of vortex gas to impart a vortical motion to the particulate material discharged from the nozzle. A trigger on the apparatus operates first and second gas valves. The first valve controls a stream of gas to the vortex gas passages in the nozzle for controlling the pattern of the sprayed material and the second valve operates a pneumatic control to cause a high voltage to be applied to the electrode in the nozzle and to cause a pump to deliver to the nozzle inlet a stream of gas having the particulate material dispersed therein. In a preferred form, the trigger opens the first valve before the second valve and closes the second valve before the first valve. Provision is made for easily cleaning residual material from the pump, the nozzle and an interconnecting tube when changing the material to be sprayed.