Highly concentrated supersonic liquified material flame spray method and apparatus
AssigneeBrowning Engineering Corporation
InventorJames A. Browning
Life of this patent
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Abstract
Within ultra high velocity flame spray apparatus, the oxy-fuel products of combustion under pressure exit from an internal burner and pass through a spray nozzle of extended length. Metal or ceramic material in thin diameter rod form or as particles are fed to the nozzle inlet at a point at or just ahead of the throat of the nozzle bore. The exceptionally long nozzle flow path and the mode of introduction of the material into the flame spray insures a concentrated and highly focussed core of spray material for material spray coating downstream of the nozzle at supersonic speed.
Claims17
In a flame spray method comprising the steps of:
- continuously combusting, under pressure, a continuous flow of an oxy-fuel mixture confined within an essentially closed internal burner combustion chamber,
- discharging the hot combustion product gases from the combustion chamber through a flow expansion nozzle as a high velocity hot gas stream, and
- feeding material to said stream for high temperature heat softening or liquefaction and spraying at high velocity onto a surface positioned in the path of the stream at the discharge end of the nozzle,
- the improvement wherein the step of feeding said material comprises introducing said material in solid form outside of said combustion chamber and axially into a converging flow of hot combustion product gases after exit from the combustion chamber while entering a converging portion of the flow expansion nozzle having a nozzle bore of a length that is at least five times that of the nozzle bore throat, to restrict the diameter of the column of particles passing through the nozzle bore, to prevent build-up of particle material on the nozzle bore wall while insuring sufficient particle dwell time within the bore to effect particle heat softening or melting and flow at supersonic flow velocity prior to impact against said surface.
A highly concentrated supersonic material flame spray apparatus comprises:
- a spray gun body,
- a high pressure essentially closed combustion chamber within said body,
- means for continuously flowing an oxy-fuel mixture under high pressure through said combustion chamber for ignition within said chamber,
- said body including combustion chamber products of combustion discharge passage means at one end thereof,
- said body further comprising an elongated nozzle downstream of said combustion chamber discharge passage means, said nozzle including a converging inlet bore portion leading to a throat and having an extended length outlet bore portion, and wherein said bore has a length that is at least five times the diameter of said nozzle bore throat,
- said combustion chamber discharge passage means comprising means for conveying a converging flow of the discharging hot products of combustion, after exit from the combustion chamber into the entrance of the nozzle inlet bore portion and means for introducing material in solid form outside of the combustion chamber axially into the hot combustion gases for subsequent heat softening or melting and acceleration with the point of introduction of the solid material being at the entrance to or within the converging inlet portion of the bore of said nozzle to restrict the diameter of the column of particles passing through the nozzle bore, prevent build-up of particle material on the nozzle bore wall while insuring sufficient particle dwell time within the gas stream to effect particle heat softening or melting prior to particle impact on a substrate downstream of the discharge end of the nozzle bore.
Dependencies are inferred from the claim text.