Abstract:
A spray gun for applying solid particles to an article includes a handle and a barrel member. The passageway for conveying a suspension of solid particles in a carrier gas is an elongated flexible tube which extends from the spray nozzle through a bore in the barrel member, the handle and outwardly from the gun to the source of coating material particles. Such a gun can also include an elongated insulator forming a passageway for highvoltage circuit means within the gun and curved between the grip portion of the handle and another bore in the barrel. A closure means of insulating material at the front of the barrel can include a portion projecting into the barrel to provide electrical insulation for the connection between the high-voltage circuit means and an electrode mounted on the front of the spray gun. The closure means can also provide a means for attaching a spray nozzle at the front of the gun.
Abstract:
A spray gun for electrostatic coating of objects with atomized solid particles comprises a tube of electrically insulating material, the free end of the tube supporting an atomizer for the coating material and the other end being connected to conveying means for supplying coating material by means of a propellant gas stream. A high-voltage generator and electrodes are provided for the electric charging of the coating material and for maintaining a high-voltage field between the gun and the object to be coated. A plurality of electrodes are disposed on the internal wall of said electrically insulating tube and are connected to potentials of different amplitudes for producing corona discharge within the tube. The electrodes preferably are formed as spikes of tungsten successively projecting from the internal wall of the tube in the direction of flow of the propellent gas-coating material mixture, each electrode being connected to one stage of a voltage divider or voltage multiplier circuit so that the successive electrodes have an increasing potential relative to a reference potential.
Abstract:
A nozzle for a powder spray gun having an elongated orifice from which a gas suspension of the powder is discharged in a flat, fanlike spray. The nozzle includes means adjacent the orifice inside the nozzle to force convergence of the suspension at the orifice and means in the flow of the suspension rearwardly from orifice cooperating with the means forcing convergence of the suspension to promote uniformity of powder distribution in the spray. The powder spray gun may include a suitable electrode adapted for connection to a high-voltage source to charge and promote the deposition of the powder particles in the spray.
Abstract:
Dry nonconductive powder passes from a hopper by means of a vibrating plate through an adjustable, nonclogging eductor and is directed by means of a current of air issuing through a rectangular orifice from a variable volume plenum chamber into a venturi. The powder particles pass into the entrance of the venturi in a stream of air having a rectangular flow pattern or cross section and from the venturi through a discharge nozzle and from the discharge nozzle onto a substrate to be coated. Corona wires are located in the proximity of the issuing end of the discharge nozzle so as to charge the powder particles in order to direct them onto a substrate. A positive draft is maintained downstream from the venturi entrance and serves to pick up excess powder particles which are pneumatically conveyed back to the feed hopper.
Abstract:
This disclosure provides an apparatus, system, and method for thermal spraying a metal cladding on a substrate. The apparatus may include a housing having a first electrode and a second electrode disposed in the housing. The second electrode can be spaced apart from the first electrode. The apparatus includes a first contact tip removably attached to the first electrode and a second contact tip removably attached to the second electrode. The position of the first contact tip and second contact tip is configured to be selectively adjusted on the first electrode and the second electrode to provide a plurality of contact surfaces for a feedstock wire. The apparatus includes a nozzle between the first contact tip and the second contact tip. The first contact tip and the second contact tip are configured to contact and deflect a wire towards the nozzle.
Abstract:
An apparatus for feeding powder particles includes a hopper holding a supply of powder. A voltage supply is in electrical communication with a first electrode and a second electrode. The hopper is configured to drop powder onto the first electrode. The voltage supply is capable of producing an electric potential between the first electrode and second electrode and causing the powder particles landing on the first electrode to develop a surface charge. The second electrode is positioned remotely from the first electrode such that the electric field between the first electrode and the second electrode causes the powder particles that fall onto the first electrode to move off the first electrode and move toward the second electrode. The powder particles moving toward the second electrode may or may not reach the electrode, but in either case drop away from the second electrode due to the force of gravity.