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Arc thermal spray gun and gas cap therefor

  • US 5,964,405 A
  • Filed: 02/20/1998
  • Issued: 10/12/1999
  • Est. Priority Date: 02/20/1998
  • Status: Expired due to Term
First Claim
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1. An arc spray apparatus comprising a spray gun body, a pair of tubular wire guides held convergingly by the gun body so as to guide two metal wires to a point of contact at spraying tips of the wires, a wire feeding mechanism operatively connected to feed the wires respectively through the wire guides, primary gas channeling in the gun body on a central axis located centrally with respect to the wire guides, and a gas cap attached to the gun body coaxially with the central axis, the wires being receptive of an arc current to effect an arc and thereby molten metal at the spraying tips, the primary gas channeling being receptive of a primary source of compressed gas to issue a primary gas flow for atomization of the molten metal and production of a spray stream thereof, the gas cap having a plurality of at least four orifices arcuately spaced equally about the central axis, the orifices being simultaneously receptive of a secondary source of compressed gas and having orifice axes oriented at an angle with the central axis such that the orifices direct secondary gas jets inwardly with a forward directional component toward a point of intersection of the orifice axes on the central axis, the point of intersection being located proximate the point of contact and spaced downstream therefrom sufficiently for the jets not to interfere substantially with the arc and the atomization, and the orifices being of circular cross section with substantially equal dimensions and having an aspect ratio of length to diameter, with the aspect ratio being sufficiently high and the angle being selected so that, with sufficient secondary gas pressure, the spray stream is constricted with substantially circular cross section and accelerated by the secondary gas jets.

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