Air spray painting apparatus

Abstract

An air spray painting apparatus for sending a fan of atomized paint spray via a first entrainment flow of carrier fluid and of a second flow of carrier fluid, separate from the first entrainment flow and capable of forming the spray fan, includes electrical heating elements for heating to one and the same temperature the first and second flows of carrier fluid, and a unit for regulation and control of the heating elements.

Claims

1. An apparatus for air spray painting of a substrate, the apparatus comprising: at least one spray dispenser configured to send a spray fan of liquid atomized paint, the dispenser being provided with at least one first nozzle and at least one second nozzle supplied by respective separate ducts to issue, respectively, a first flow of carrier fluid to entrain the paint and a second flow of carrier fluid, separate from said first entrainment flow, to confine the spray fan externally, said first and second flows being supplied at pressures regulated independently; a temperature conditioning system set upstream in the proximity of the dispenser, the temperature conditioning system being configured to condition the temperature of said first and second flows of carrier fluid to the same temperature; and a temperature regulation and control system configured to regulate and control the temperature induced in the flows of carrier fluid by said temperature conditioning system.

2. The apparatus according to claim 1, wherein said temperature conditioning system comprises an electrical heater.

3. The apparatus according to claim 1, wherein said temperature conditioning system comprises a cooling system.

4. The apparatus according to claim 2, wherein said heater comprises a two-way coil constituted by two tubes made of thermally conductive material set along said ducts for the first and second flows, set in contact with a common electrical resistance that is wound around the tubes in order to maintain a temperature common to said first and second flows.

5. The apparatus according to claim 1, further comprising first and second independent ionization systems configured to electrostatically charge the first and second flows of carrier fluid by emission of negative, or positive, or neutral-state ions.

6. The apparatus according to claim 5, wherein the emission of ions by said ionization systems is controlled and regulated by said temperature regulation and control system.

7. The apparatus according to claim 5, wherein said ionization systems respectively comprise a first ionization chamber and a second ionization chamber associated to said respective first and second flows, and a first ionizing device and a second ionizing device configured to introduce into said respective first and second ionization chambers negative, or positive, or neutral-state ions and electrostatically charge said first and second flows of carrier fluid.

8. The apparatus according to claim 5, wherein said temperature conditioning system comprises an electrical heater, and said heater and said ionization systems are integrated in a heating and ionization device provided with inlets and outlets for said first and second flows of carrier fluid and with connections to said temperature regulation and control system unit.

9. The apparatus according to claim 1, wherein said temperature conditioning system comprises an electrical heater, and said heater being supplied with a voltage equal to or less than 48 V.

10. The apparatus according to claim 1 for electrostatic painting of substrates set in a painting area, the apparatus further comprising: a supply of a pressurized carrier fluid located in an area outside said painting area; a pressure regulation and control system configured to regulate and control the pressures of said carrier fluids, the pressure regulation and control system receiving via a supply duct a flow of carrier fluid from said supply and providing at least one first outlet and one second outlet for carrier fluid at the independently controlled pressures, wherein the at least one spray dispenser is located in said painting area, the at least one spray dispenser being provided with an operative end equipped with the at least one first nozzle communicating by first ducts with said first outlet and communicating with a supply of liquid paint to send onto said substrate a fan of paint spray atomized by the first entrainment flow of carrier fluid, the at least one spray dispenser being provided with the at least one second nozzle set alongside said first nozzle and communicating by second ducts with said second outlet of pressurized carrier fluid to issue the second flow of carrier fluid, separate from said first entrainment flow and capable of forming said spray fan, and wherein the temperature conditioning system is a low-voltage heater located in said painting area.

11. The apparatus according to claim 10, wherein said supply comprises a device configured to supply the flow of carrier fluid constituted by a mixture made up of nitrogen in a range of 80-98%, oxygen in a range of 1-19%, and argon in a range of 1-2% obtained by continuous separation starting from a flow of compressed air taken in from the environment during painting deprived of residual substances.

12. An integrated system for thermal conditioning and ionization of a carrier fluid for electrostatic air spray painting provided with inlets and outlets for a first flow and a second flow of a carrier fluid, the integrated system comprising: a temperature conditioning system configured to condition the temperature of a first flow of carrier fluid and a second, separate, flow of carrier fluid to the same temperature; and first and second independent ionization systems configured to electrostatically charge the first and second flows of carrier fluid with negative, or positive, or neutral-state ions, wherein said temperature conditioning system and said ionization systems are connected via connections to a temperature regulation and control system configured to regulate and control said temperature and said ionization charges.

13. The integrated system according to claim 12, wherein said temperature conditioning system comprises an electrical heater.

14. The integrated system according to claim 12 wherein said temperature conditioning system comprises a cooling system.

15. The integrated system according to claim 13, wherein: said electrical heater comprises a two-way coil constituted by two tubes made of thermally conductive material, the tubes being set in contact with a common electrical resistance that is wound around the tubes.

16. The integrated system according to claim 12, wherein: said ionization systems respectively comprise a first ionization chamber and a second ionization chamber associated to said respective first and second flows, and a first ionizing device and a second ionizing device configured to introduce into said respective first and second ionization chambers negative, or positive, or neutral-state ions and electrostatically charge said first and second flows of carrier fluid.

17. The apparatus according to claim 2, wherein said temperature conditioning system comprises a cooling system.

18. The integrated system according to claim 13, wherein said temperature conditioning system comprises a cooling system.

Description

LIST OF THE DRAWINGS

(1) The above and further advantages will be better understood by any person skilled in the branch from the ensuing description and from the annexed drawings, which are provided by way of non-limiting example and in which:

(2) FIG. 1 is a schematic illustration of an apparatus according to the invention;

(3) FIG. 2-4 show, respectively, a perspective view, a side view, and a front view of a heating and ionization unit according to the invention,

(4) FIG. 5 shows a detail of a two-way heating coil;

(5) FIG. 6 shows a heating and ionization unit and the corresponding control unit according to the invention; and

(6) FIG. 7 shows a detail of an example of paint-spray dispenser.

DETAILED DESCRIPTION

(7) With reference to the drawings, described hereinafter is an apparatus for electrostatic painting of substrates 1 arranged in a painting area A1, for example substrates conveyed by a robotized conveying system 33 within a painting tunnel closed by walls 34 that separate it from an external area A2.

(8) Installed in the external area A2 is a generator of carrier fluid 2, comprising, for example, hollow-fibre separation membranes and/or PSA separation systems for modifying an incoming flow 40 of compressed ambient air.

(9) Preferably, the carrier fluid is constituted by a mixture made up of nitrogen in a range of 80-98%, oxygen in a range 1-19%, and argon in a range 1-2% obtained by continuous separation starting from a flow of compressed air taken in from the environment deprived of residual substances not comprised in the composition appearing in the table given above.

(10) The generator 2 is operatively connected to a unit 14 for regulation and control of the pressure of the fluid, which receives via a duct 13 the flow of carrier fluid generated and makes available at least two independent outlets 15, 16 for the carrier fluid at pressures P1, P2 controlled independently.

(11) Starting from the outlets 15, 16 are two separate ducts 8, 9, which convey the flows up to a dispenser or gun, 4 located in the painting area A1.

(12) The gun 4 (FIG. 7) is provided with an operative end 38 where there gives out a first nozzle 5 communicating with a first outlet 15 of carrier fluid and with a supply of liquid paint 3. The carrier fluid conveyed by the duct 8 has the function of atomizing the paint in a mixing point 39 and entraining it onto the substrate 1 with a fan of atomized paint 12. The shape of the fan 12 is determined by a second flow of carrier fluid coming out of nozzles 6 set alongside the spray nozzle 5 and communicating by means of the ducts 9 with the second outlet 16 of the control unit 14.

(13) According to the invention, the temperature of two distinct flows 8, 9 of carrier fluid are heated to the same temperature by means of a low-voltage electrical-heating assembly 10 preferably located within the painting area A1 in the proximity of the gun 4 and connected to a regulation and control unit 11 located in the external area A2.

(14) According to the invention, the temperature of two distinct flows 8, 9 of carrier fluid are adjusted and kept to the same temperature by means of temperature conditioning means 10 (heating and/or cooling means comprising by example a chiller) preferably located within the painting area A1 in the proximity of the gun 4 and connected to a regulation and control unit 11 located in the external area A2.

(15) Advantageously, with the solution described, the temperature conditioning means comprise heating device 10 enabling the temperature to be kept constant for the two flows of fluid that reach the spray gun with pressures controlled independently, thus optimizing the painting process consisting of the step of atomization and the step of formation of the fan.

(16) In a preferred embodiment, the heating assembly comprises a two-way coil 19 constituted by two tubes 20, 21 made of thermally conductive material, for example copper, which are traversed, respectively, by the flows 8, 9 of the carrier fluid, are set in mutual contact, and around which a common electrical resistance 22 is wound, for example a 500-W resistance (FIG. 5) at a temperature ranging from 0 C. to 100 C. supplied by a voltage equal to or less than 48 V.

(17) According to the invention, it is moreover envisaged to equip the apparatus with independent ionization units 17, 18 controlled by said regulation and control unit 11 for electrostatically charging the first and second flows of carrier fluid with negative, or positive, or neutral-state ions.

(18) Advantageously, with this solution it is possible to charge the preheated fluid electrostatically without the latter presenting any interference due to apparatuses for regulating the pressures set upstream of the unit 27, and without the apparatus modifying the pre-set pressure values.

(19) In an example of embodiment (FIG. 2-4), the ionization units 17, 18 comprise, respectively, a first ionization chamber 23 and a second ionization chamber 23, 24 associated to said respective first and second flows, and a first ionizing device 25 and a second ionizing device 26 provided with connections 41, 42 to the ionization chambers for introducing negative, or positive, or neutral-state ions and electrostatically charging said first and second flows of carrier fluid in a uniform or non-uniform way, according, for example, to the substrate to be painted or to the painting environment.

(20) Advantageously, the heating assembly 10 and the ionization units 17, 18, are integrated in a heating and ionization unit 27 provided with inlets 28, 29 and outlets 30, 31 for the flows of entrainment carrier fluid and spray-fan carrier fluid and with connections 32 to the regulation and control unit 11.

(21) In operation of the unit 27, the separate flows of carrier fluid enter the inlets 28, 29 and traverse the device 10, heating up to one and the same temperature regulated and maintained via the regulation and control unit 11.

(22) The flows of heated fluid are introduced into the ionization chambers 23, 24 via ducts 43, 44 connected to the tubes 20, 21 of the assembly 10 and come out therefrom via further ducts 45, 46 that lead to the outlets 30, 31 of the unit 27.

(23) The present invention has been described according to preferred embodiments, but equivalent variants may be devised, without thereby departing from the sphere of protection of the invention.