Electrostatic resin powder spray system

Claim 2

An electrostatic spray system for coating an article with resin comprising, in combination, an electrostatic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means including a spray booth and powder separator means for recovering overspray resin powder particles ejected from said nozzles which do not contact said article and for delivering them to said supply hopper, conveyor means for moving said article through said spray booth past said nozzle, means responsive to the presence of said article opposite saId nozzle for controlling said powder supplying means to deliver resin powder to said nozzle and responsive to the absence of said article opposite each nozzle to shut off said powder supply, whereby a minimum of overspray powder is circulated in said powder recovery system, means for supplying new resin powder to said system, and means responsive to the level of new and recovered powder in said supply hopper for controlling said new powder supplying means.

Claim 3

An electrostatic spray coating system in accordance with claim 1 wherein said means for supplying new powder to said supply hopper includes a hopper for new powder registering with said supply hopper, a powder dispensing valve between said new powder hopper and said supply hopper, and wherein said means for controlling said new powder supplying means includes powder level detecting means in said supply hopper for operating said powder dispensing valve when the new and recovered powder in said supply hopper is below a predetermined level.

Claim 4

An electrostatic spray resin coating system in accordance with claim 2 wherein said means for recovering overspray resin particles includes a bin for recirculated powder disposed above said supply hopper, conduit means connecting said powder separator and said recirculated powder bin, and a vibrating screen in said recirculated powder bin disposed between said conduit means and said supply hopper.

Claim 5

A system in accordance with claim 1 wherein said means for supplying new powder to said supply hopper includes a flexible conduit screw conveyor and a motor for driving said screw conveyor and said means responsive to the level of new and recovered powder controls the energization of said motor.

Claim 6

A system in accordance with claim 4 wherein said means responsive to the level of new and recovered powder includes a vibratory rod probe depending to a predetermined level in said supply hopper, electric exciter coil means for inducing sustained oscillations in said rod probe when it is uncovered, and electric pickup coil means for generating an output signal in response to oscillations of said rod probe.

Claim 7

An electrostatic spray coating system in accordance with claim 1 wherein said powder separator includes filter means on which said overspray resin particles can temporarily collect and means for intermittently cleaning said filter means and said means for recovering overspray particles includes screening means disposed between said powder separator and said supply hopper for removing coarse, agglomerated particles from said powder and the discharge end of said means for supplying new powder is above said screening means.

Claim 8

A system in accordance with claim 6, wherein said means for recovering overspray resin particles includes means for creating negative pressure in said powder separator to draw overspray resin particles into said separator and continuously operating valve means disposed between said powder separator and said screening means.

Claim 9

A system in accordance with claim 7 wherein said supply hopper has a steeply sloping flexible sidewall and vibratory means for flexing said sidewall.

Claim 10

An electrostatic spray coating system in accordance with claim 6 wherein said powder separator includes a housing, a plurality of depending inflatable bags within said housing, and means for intermittently inflating said bags.

Claim 11

An electrostatic spray system for coating an article with resin comprising, in combination, an electrostatic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means including a spray booth for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for Delivering them to said supply hopper, means for feeding new powder to said supply hopper, a motor for actuating said new powder feeding means, level detecting means responsive to the level of new and overspray resin powder in said supply hopper for controlling the energization of said motor, means responsive to the presence of said article opposite said nozzle for controlling said powder supplying means to deliever resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply whereby a minimum of overspray powder is circulated in said powder recovering means, and conveyor means for moving said article through said spray booth past said nozzle.

Claim 12

An electrostatic spray system for coating an article with resin comprising, in combination, an electrostatic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means including a spray booth for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for Delivering them to said supply hopper, means for feeding new powder to said supply hopper, a motor for actuating said new powder feeding means, level detecting means responsive to the level of new and overspray resin powder in said supply hopper for controlling the energization of said motor, means responsive to the presence of said article opposite said nozzle for controlling said powder supplying means to deliever resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply whereby a minimum of overspray powder is circulated in said powder recovering means, and conveyor means for moving said article through said spray booth past said nozzle.

Claim 13

A system in accordance with claim 10 wherein said means for recovering overspray resin particles includes a vibratory screen above said supply hopper for removing coarse agglomerated particles from said powder.

Claim 14

A system in accordance with claim 11 wherein said means for feeding new powder includes a flexible tubular conduit having its discharge end above said vibratory screen, a screw conveyor in said flexible conduit, and a motor for driving said screw conveyor, and wherein said powder level detecting means controls the energization of said motor.

Claim 15

A system in accordance with claim 11 wherein said level detecting means includes a vibratory rod probe depending to a predetermined level in said supply hopper, electric exciter coil means for generating sustained oscillations in said rod probe when it is uncovered, and electric pickup coil means for generating an output signal in response to the oscillations in said rod probe.

Claim 16

An electrostatic spray coating system in accordance with claim 10 wherein said means for supplying resin powder to said nozzle includes venturi means communicating with said supply hopper, conduit means between said venturi means and said nozzle, a source of pressurized air, and valve means between said pressurized air source and said venturi means controlled by said means responsive to the presence of said article opposite said nozzle.

Claim 17

An electrostatic spray system for coating an article with resin comprising, in combination, an electrostatic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for delivering them to said supply hopper, means responsive to the absence of said article opposite said nozzle for controlling said powder supplying means to deliver resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply, whereby a minimum of overspray powder is circulated in said powder recovery means, means for feeding new powder to said supply hopper, and level detecting means responsive to the level of new and recovered powder in said supply hopper for controlling said means for feeding new powder;

Claim 18

An electrostatic spray system for coating an article with resin comprising, in combination, an electrostatic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for delivering them to said supply hopper, means responsive to the absence of said article opposite said nozzle for controlling said powder supplying means to deliver resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply, whereby a minimum of overspray powder is circulated in said powder recovery means, means for feeding new powder to said supply hopper, and level detecting means responsive to the level of new and recovered powder in said supply hopper for controlling said means for feeding new powder;

Claim 19

An electrostatic spray resin coating system in accordance with claim 15 wherein said means for recovering overspray resin powder particles includes screening means above said supply hopper for removing coarse particles from said powder and wherein said means for feeding new powder has its discharge end above said screening means.

Claim 20

An electrostatic spray coating system in accordance with claim 16 wherein said means for feeding new powder includes a flexible conduit having its discharge end above said screening means, a screw conveyor within said flexible conduit, a motor for driving said screw conveyor, and wherein said powder level detecting means controls the energization of said motor.

Claim 21

An electrostatic spray coating system in accordance with claim 16 wherein said powder level detecting means includes a vibratory rod probe depending to a predetermined level within said supply hopper, electric exciter coil means for generating sustained oscillations in said rod probe when it is uncovered, and electric pickup coil means for generating an output signal in response to the oscillations in said rod probe.

Claim 22

A system according to claim 16 wherein said means for supplying powder to said nozzle includes venturi means communicating with said supply hopper, a conduit between said venturi means and said nozzle, a source of pressurized air for said venturi means, air valve means for supplying and shutting off said source of pressurized air to said venturi means, and wherein said means responsive to the presence of said article controls said air valve means.

Claim 23

A system according to claim 16 wherein said means for recovering overspray resin particles includes a spray booth and said means responsive to the presence of said article opposite said nozzle includes conveyor means for moving said article through said booth past said nozzle.

Claim 24

A system according to claim 20 wherein said means for recovering overspray resin powder particles includes a powder separator having a housing, a plurality of depending inflatable bags within said housing, and means for intermittently inflating said bags.

Claim 25

A system according to claim 21 and including exhaust fan means on said powder separator housing for creating negative pressure to draw overspray resin powder particles into said separator housing and continuously operating valve means at the lower end of said separator housing.

Claim 26

A system according to claim 22 wherein said powder separator housing has a flexible steeply sloping sidewall at its lower end above said continuously operating valve means and vibratory means for flexing said separator housing sidewall.

Claim 27

An electrostatic spray system for coating an article with resin comprising, in combination, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article in an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means, said powder separator having a continuously operating outlet valve leading to said second conduct means, exhaust fan means for creating negative pressure within said separator to draw overspray resin particles into said separator, a steeply sloping flexible sidewall at its lower end and above said outlet valve, vibratory means for flexing said sidewall to prevent compaction of said overspray resin powder particles, a plurality of depending inflatable bags in which said overspray resin powder particles settle, and means for intermittently inflating said bags.

Claim 28

An electrostatic spray system for coating an article with resin comprising, in combination, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article in an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means, said powder separator having a continuously operating outlet valve leading to said second conduct means, exhaust fan means for creating negative pressure within said separator to draw overspray resin particles into said separator, a steeply sloping flexible sidewall at its lower end and above said outlet valve, vibratory means for flexing said sidewall to prevent compaction of said overspray resin powder particles, a plurality of depending inflatable bags in which said overspray resin powder particles settle, and means for intermittently inflating said bags.

Claim 29

An electrostatic spray system for coating an article with resin comprising, in combiNation, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article at an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means, screening means between said powder separator and said supply hopper for removing coarse agglomerated particles from said powder, means for supplying new powder to said supply hopper and powder level detecting means responsive to the amount of new and overspray powder in said supply hopper for controlling said new powder supplying means.

Claim 30

An electrostatic spray system for coating an article with resin comprising, in combiNation, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article at an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means, screening means between said powder separator and said supply hopper for removing coarse agglomerated particles from said powder, means for supplying new powder to said supply hopper and powder level detecting means responsive to the amount of new and overspray powder in said supply hopper for controlling said new powder supplying means.

Claim 31

A system in accordance with claim 25 wherein said new powder supplying means includes a bin for new powder, powder dispensing valve means between said new powder bin and said supply hopper, and said powder level detecting means controls said powder dispensing valve means.

Claim 32

A system in accordance with claim 26 wherein said powder dispensing valve means rotates to dispsense new powder to said supply hopper and including variable speed motor means for driving said powder dispensing valve means and means responsive to the amount of new and recirculated powder in said supply hopper for selectively varying the speed of said motor means.

Claim 33

A system in accordance with claim 25 wherein said means for supplying new powder includes a flexible conduit screw conveyor having its discharge end above said screening means, and a motor for driving said screw conveyor and said powder level detecting means controls the energization of said motor and includes a vibratory rod probe depending to a predetermined level within said supply hopper, electric exciter coil means for inducing sustained oscillations in said rod probe when said probe is uncovered, and electric pickup coil means for generating an output signal in response to the oscillations in said rod probe.

Claim 34

A system in accordance with claim 25 wherein said supply hopper has a steeply sloping flexible sidewall and including vibratory means for flexing said sidewall to prevent compaction of said powder in said supply hopper.

Claim 35

An electrostatic spray system for coating an article with resin comprising, in combination, an electrosattic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for delivering them to said supply hopper and including a spray booth and powder separator means for returning overspray powder particles to said supply hopper, said powder separator means having filter means on which said overspray resin powder partIcles can temporarily collect and means for intermittently cleaning said filter means, and means responsive to the presence of said article opposite said nozzle for controlling said powder supplying means to deliver resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply, whereby a minimum of overspray powder is circulated in said powder recovering means.

Claim 36

An electrostatic spray system for coating an article with resin comprising, in combination, an electrosattic resin powder spray nozzle, a supply hopper for new and recovered resin powder, means communicating with said supply hopper for supplying resin powder to said nozzle, means for electrostatically charging resin powder particles ejected from said nozzle, means for maintaining said article at a potential which will attract said charged resin particles to it, means for recovering overspray resin powder particles ejected from said spray nozzle which do not contact said article and for delivering them to said supply hopper and including a spray booth and powder separator means for returning overspray powder particles to said supply hopper, said powder separator means having filter means on which said overspray resin powder partIcles can temporarily collect and means for intermittently cleaning said filter means, and means responsive to the presence of said article opposite said nozzle for controlling said powder supplying means to deliver resin powder to said nozzle and responsive to the absence of said article opposite said nozzle to shut off said powder supply, whereby a minimum of overspray powder is circulated in said powder recovering means.

Claim 37

An electrostatic spray system for coating an article with resin comprising, in combination, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article at an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, filter means on which said overspray resin powder particles can temporarily collect, and means for intermittently cleaning said filter means, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, and means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means.

Claim 38

An electrostatic spray system for coating an article with resin comprising, in combination, a spray booth, a resin powder spray nozzle within said booth, conveyor means for moving an article to be coated through said booth past said nozzle, means for electrically charging resin powder particles ejected from said nozzle, means for maintaining said article at an electric potential which will attract said charged resin particles to it, a powder separator, means including first conduit means between said spray booth and said powder separator for recovering overspray resin particles ejected from said nozzle which do not contact said article and for delivering them to said powder separator, filter means on which said overspray resin powder particles can temporarily collect, and means for intermittently cleaning said filter means, a supply hopper for new and recovered powder, second conduit means communicating at one end with said powder separator and at the other end with said supply hopper, means including a venturi communicating with said supply hopper and a source of pressurized air for said venturi for supplying powder from said supply hopper to said nozzle, air valve means for selectively connecting and shutting off said source of pressurized air to said venturi, and means responsive to the presence of said article opposite said nozzle for opening said air valve means and to the absence of said article opposite said nozzle for closing said air valve means.