Electrostatic coating methods and apparatus

Claim 1

THE METHOD OF ELECTROSTATICALLY SPRAY-COATING AN ARTICLE WHICH COMPRISES CONTINUOUSLY SUPPLYING LIQUID COATING MATERIAL UNDER HIGH HYDROSTATIC PRESSURE OF AT LEAST TWO HUNDRED FIFTY POUNDS PER SQUARE INCH TO A SMALL ORIFICE IN A SINGLE-FLUID ATOMIZING HEAD, SAID ORIFICE HAVING AN EFFECTIVE OPENING EQUIVALENT TO A CIRCULAR ORIFICE OF NOT GREATER THAN ABOUT FIFTEEN THOUSANDTHS OF AN INCH IN DIAMETER, PROJECTING THE COATING MATERIAL THEREFROM INTO THE SURROUNDING ATMOSPHERE WITH A VERY HIGH VELOCITY, THE COATING MATERIAL FORMING A THIN EXPANDING FILM WITH GENERALLY STRAIGHT SIDES DEFINING AN ANGLE OF AT LEAST 15* AND HAVING A FORWARD EDGE, THE THICKNESS OF SAID FILM BEING LESS THAN THE TRANSVERSE, EXTENT THEREOF THROUGHOUT THE LENGTH OF SAID FILM TO EFFECT ATOMIZATION OF THE COATING MATERIAL FROM SAID EDGE INTO FINE SPRAY PARTICLES, THE DISTANCE OF THE CENTER OF SAID FILM EDGE FROM SAID ORIFICE BEING NOT IN EXCESS OF ABOUT THREE-QUARTERS OF AN INCH, WHEREBY THE PARTICLES ARE OF A SIZE PROVIDING ON DEPOSITION A SPRAY SPOT OF NOT GREATER THAN OF THE ORDER OF TWENTY THOUSANDTHS OF AN INCH IN DIAMETER, EFFECTING RELATIVE MOVEMENT BETWEEN SAID HEAD AND THE ARTICLE SURFACE TRANSVERSE TO THE GENERAL DIRECTION OF SPRAY PARTICLE MOVEMENT WHILE MAINTAINING THE SPACE BETWEEN THE ARTILCE SNAD SAID HEAD GREAT ENOUGH TO PERMIT SUBSTANTIAL DISPERSION OF THE SPRAY PARTICLES AND AT LEAST SEVERAL INCHES, MAINTAINING A QUIESCENT ATMOSPHERE ADJACENT THE ARTICLE, AND PROVIDING AN ELECTROSTATIC CHARGING FIELD HAVING AN AVERAGE GRADIENT OF THE ORDER OF FIVE THOUSAND VOLTS PER INCH ELECTROSTATICALLY TO CHARGE AND CARRY THROUGH SAID QUIESCENT ATMOSPHERE AND DEPOSIT ON SAID ARTICLE WHILE STILL IN LIQUID STATE A SUBSTANTIAL PORTION OF THE SPRAY PARTICLES WHICH WOULD NOT OTHERWISE HAVE BEEN DEPOSITED THEREON, THE RELATIVE MOVEMENT BEING SUCH AS TO EFFECT A SUBSTANTIAL DISPLACEMENT BETWEEN THE ARTICLE SURFACE AND HEAD TRANSVERSE TO THE GENERAL DIRECTION OF SPRAY PARTICLE MOVEMENT DURING PARTICLE DEPOSITION.

Claim 2

THE METHOD OF ELECTROSTATICALLY SPRAY-COATING AN ARTICLE WHICH COMPRISES CONTINUOUSLY SUPPLYING LIQUID COATING MATERIAL UNDER HIGH HYDROSTATIC PRESSURE OF AT LEAST TWO HUNDRED FIFTY POUNDS PER SQUARE INCH TO A SMALL ORIFICE IN A SINGLE-FLUID ATOMIZING HEAD, SAID ORIFICE HAVING AN EFFECTIVE OPENING EQUIVALENT TO A CIRCULAR ORIFICE OF NOT GREATER THAN ABOUT FIFTEEN THOUSANDTHS OF AN INCH IN DIAMETER, PROJECTING THE COATING MATERIAL THEREFROM INTO THE SURROUNDING ATMOSPHERE WITH A VERY HIGH VELOCITY, THE COATING MATERIAL FORMING A THIN EXPANDING FILM WITH GENERALLY STRAIGHT SIDES DEFINING AN ANGLE OF AT LEAST 15* AND HAVING A FORWARD EDGE, THE THICKNESS OF SAID FILM BEING LESS THAN THE TRANSVERSE, EXTENT THEREOF THROUGHOUT THE LENGTH OF SAID FILM TO EFFECT ATOMIZATION OF THE COATING MATERIAL FROM SAID EDGE INTO FINE SPRAY PARTICLES, THE DISTANCE OF THE CENTER OF SAID FILM EDGE FROM SAID ORIFICE BEING NOT IN EXCESS OF ABOUT THREE-QUARTERS OF AN INCH, WHEREBY THE PARTICLES ARE OF A SIZE PROVIDING ON DEPOSITION A SPRAY SPOT OF NOT GREATER THAN OF THE ORDER OF TWENTY THOUSANDTHS OF AN INCH IN DIAMETER, EFFECTING RELATIVE MOVEMENT BETWEEN SAID HEAD AND THE ARTICLE SURFACE TRANSVERSE TO THE GENERAL DIRECTION OF SPRAY PARTICLE MOVEMENT WHILE MAINTAINING THE SPACE BETWEEN THE ARTILCE SNAD SAID HEAD GREAT ENOUGH TO PERMIT SUBSTANTIAL DISPERSION OF THE SPRAY PARTICLES AND AT LEAST SEVERAL INCHES, MAINTAINING A QUIESCENT ATMOSPHERE ADJACENT THE ARTICLE, AND PROVIDING AN ELECTROSTATIC CHARGING FIELD HAVING AN AVERAGE GRADIENT OF THE ORDER OF FIVE THOUSAND VOLTS PER INCH ELECTROSTATICALLY TO CHARGE AND CARRY THROUGH SAID QUIESCENT ATMOSPHERE AND DEPOSIT ON SAID ARTICLE WHILE STILL IN LIQUID STATE A SUBSTANTIAL PORTION OF THE SPRAY PARTICLES WHICH WOULD NOT OTHERWISE HAVE BEEN DEPOSITED THEREON, THE RELATIVE MOVEMENT BEING SUCH AS TO EFFECT A SUBSTANTIAL DISPLACEMENT BETWEEN THE ARTICLE SURFACE AND HEAD TRANSVERSE TO THE GENERAL DIRECTION OF SPRAY PARTICLE MOVEMENT DURING PARTICLE DEPOSITION.