Method of spray coating using laser-energy beam

#This invention relates generally to electronic flames or radio frequency (R.F.) energy beams in combination with laser beams to provide an energy system for communications, for heating and for otherwise operating on workpieces. Much of the background of the R.F. energy beam portion of this invention may be found in the U.S. Pat. No. 3,648,015, issued to Thomas E. Fairbairn on Mar. 7, 1972.

#The R.F. energy portion of the beam, which is generally known, is generated by a conventional radio frequency having a tank coil in its output circuit. The tank coil is a hollow metal tube into which inert gas is introduced under pressure. The output of the tank coil is coupled through a nozzle having an electrode mounted therein, and upon application of power to the radio frequency generator, an R.F. electron energy beam is emitted from the tip of the electrode and this beam is sheathed and focused by the inert gas.

#Unsuccessful attempts have been made to treat certain metals with lasers prior to my invention. For example, it is not yet possible to perform deep penetration welding of aluminum with only a laser, because aluminum has a mirror like finish, and lasers have a high index for reflection off of aluminum. Furthermore, the present laser welding units, to weld other metals, require lasers generating in excess of 10 kilowatts of power at a cost of about $50 per watt, or a total cost in excess of $500,000.

#The foregoing objects of the present invention, together with other objects and advantages which may be attained by its use, will become more apparent upon reading the following detailed description taken in conjunction with the drawings.

#In the drawings, wherein like reference numerals identify corresponding parts:

#FIG. 1 is a diagrammatic illustration of the laser-R.F. energy beam torch of the present invention;

#The laser beam-radio frequency energy beam system of the present invention includes a radio frequency generator 10 having a conventional output tank circuit 11 and a tank coil 12. The choice of the particular radio frequency generator may be made by those killed in the art as long as a coherent single frequency R.F. sine wave is the output. An exemplary circuit is shown in my U.S. Pat. No. 3,648,015 which is hereby incorporated by reference. The tank coil is a hollow copper tubing both ends of which are electrically and mechanically connected to the tank circuit as at 13.

#In addition to the electrical input to the tank coil 12 supplied by the R.F. generator 10, there is a pressurized fluid input provided from a fluid supply 14. The fluid may be water or may be a gaseous media such as oxygen, propane or hydrogen, or other inert gas. An inert gas such as air or helium is preferred. A fluid path is defined from a tube 16 through a T-fitting 18 and a supply tube 20 to a low voltage, high current point on the tank coil 12. Inert gas under very low pressure is introduced at a low voltage point of the tank coil to prevent ionization of the gas with its resultant effect upon the fittings and the tank coil such as shorting, melting and the like.

#A powder material or other aggregate may also be introduced into the tank coil for spraying onto a workpiece, from a supply of powder 22. The powder or aggregate supply 22, together with a carrier gas 24, are supplied as inputs to a secont T-fitting 26. The output of this T-fitting goes through a tube 28 to the T-fitting 18. Thus, the powder supply, which is optional, is also introduced into a low voltage, high current point of the tank coil 12 and is conveyed in a smaller tube, not shown, within the tube or tank coil 12.