Spray device and method for powder coating material
AssigneeGema Volstatic AG
InventorEugen Thomas Buhlmann
Life of this patent
Estimating the term…
Abstract
A spray device and method for the coating of objects with powder coating material. A high voltage electrode or several electrodes are located on only one side of the coating material stream in the vicinity of a spray orifice for electrostatically charging the coating material. A first flow of compressed air is directed over the electrodes to keep the coating material from accumulating on the electrode and to shape the envelope of the sprayed coating material. A second stream of compressed air is directed at the stream of coating material to counteract the deflection of the stream by the first flow and by the effects of the high voltage. Better coating efficiency (reduced loss of sprayed powder) is achieved than with electrodes arranged on both sides of the coating material stream.
Claims15
A spray device for spraying a stream of electrostatically charged powder coating material along a flow path comprising a nozzle having a coating material flow channel terminating at a spray orifice in a downstream end for discharging a stream of powder coating material, said flow channel and said spray orifice defining a portion of the coating material flow path, a high voltage electrode located to one side of the coating material flow path adjacent said spray orifice, means for applying a high voltage to said electrode, a first duct means for directing a first flow of air over said high voltage electrode and in a direction to impinge on one side of the stream of powder coating material adjacent said orifice, a second duct means for directing a second flow of air which is free of contact with high voltage in a direction to impinge on the stream of powder coating material adjacent said orifice on a side of the stream of powder coating material diametrically opposite the first flow of air, the second flow of air counteracting the deflection of the stream of powder coating material by the first flow of air and the deflection of the stream of powder coating material caused by the exposure of the first flow of air to the high voltage.
A process for the spray coating of articles with electrostatically charged powder coating material comprising the steps of:
- a) discharging a stream of powder coating material through an orifice of a spray nozzle;
- b) applying a high voltage to an electrode located within the spray nozzle and adjacent one side of said stream of powder coating material to impart an electrostatic charge to the stream of powder coating material;
- c) directing a first flow of air to flow over said high voltage electrode and to impinge against said one side of said stream of powder coating material;
- and
- d) directing a second flow of air which is free of contact with high voltage to impinge against said stream of powder coating material on a side diametrically opposite said one side of said stream of powder coating material to counteract deflection of said stream of powder coating material caused by the exposure to the high voltage and the impingement by said first flow of air.
Dependencies are inferred from the claim text.