CA1285136C - Cleaning device upon color-change in an electrostatic multi-color coating apparatus - Google Patents
Cleaning device upon color-change in an electrostatic multi-color coating apparatusInfo
- Publication number
- CA1285136C CA1285136C CA000500949A CA500949A CA1285136C CA 1285136 C CA1285136 C CA 1285136C CA 000500949 A CA000500949 A CA 000500949A CA 500949 A CA500949 A CA 500949A CA 1285136 C CA1285136 C CA 1285136C
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- Prior art keywords
- color
- paint
- valve
- cleaning
- supply channel
- Prior art date
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Abstract
The present invention provides a cleaning device upon colorchange in an electrostatic multi-color electrostatic coating apparatus comprising: a first color change device comprising a first manifold including valves for supplying respective paints of different colors, a cleaning air, and a cleaning thinner selectively through a first paint supply channel; a second colorchange device smaller in size than said first color-change device, disposed near the electrostatic coating machine and comprising a second manifold including valves for supplying respective paints of different colors, a cleaning air and a cleaning thinner selectively through a second paint supply channel; and a valve mechanism disposed near said electrostatic coating machine for supplying a paint supplied from said first color-change device or said second color-change device selectively through said first paint supply channel or said second paint supply channel to an electrostatic coating machine by way of a common paint hose, wherein said valve mechanism comprises a third manifold in communication with said hose including a first switching valve having two exit channels selectively connectable to said first pain supply channel, a second switching valve having two exit channels selectively connectable to said second paint supply channel, and a low pressure air supply valve and a low pressure thinner supply valve, in which one of the exit channels of said first switching valve and on of the exit channels of said second switching valve are connected by way of said third manifold to said paint hose, while the other of the exit channels of said switching valves are connected by ON-OFF valves to a liquid discharge channel which leads to a liquid discharge tank adapted to supply paints of a multiplicity of colors selectively under color-change to an electrostatic coating machine having an atomizing cup applied with a high voltage and rotationally driven at a high speed.
Description
1~5~36 This invention concerns a cleaning device upon color-chanye in an electronic multi color coatiny apparatus adapted to ~upply paints of a multi,plicity of colours selectively under color-change to an e]ectrostatic coating machine having an atomizing cup applied wi-th a high voltaye and rotationally driven a-t a hiyh speed.
In an electrostatic multi-color coatiny apparatus ~or use in the coating of automobiles, -the color of paint i.5 often changed from one to another and cleaniny for t,he inside Oe the coatiny apparatus i5 necessary on every color change for avoidiny unde.sired mixing of colors. In such a case, it has been required to minimize the waste~'ul loss o~ paints upon color-chanye and to reduce the cleaniny time upon color change as short as possible. In order to satisfy the Eoreyoiny requirements, it may be considered to situate a color-change device for selectively supplying paints o~ a multiplicity of colors near the electrostatic coating machine thereby shorten the ~.
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paint supply channe], connected between the coating machlne and the color-change device 80 that the residual amount o~
paint in the paint supply channel is reduced.
However, i~ the color change device is disposed near the coating machine, an excess load is undesirably applled to a reciprocator adapted to drlve the coating machine ln accordance with a predetermined coating pattern. In view Or the above, the use Or a considerably long paint supply channel has been inevitable.
Then, ~or shortening the cleaning time upon color-change, cleaning air and cleaning thinner at high pressure have been supplied ~rom the color-change device to the paint supply channel to thereby rapidly clean the inside Or the paint supply channel and the atomizing cup.
However, such a system involves another problem that the waste~ul loss Or the paint i8 inevitable and a great amount o~ paint and cleaning thinner are violently blown out rrom the cup o~ the electrostatic coating machine because a great amount of the cleaning thinner is supplied in a short time to the inside of the paint supply channel.
They are overrlown rrom and scattered around to the outside the shroud disposed at the periphery o~ the cup o~ the coating machine ~or recovering the discharged liquid, to contaminate the peripheral equipments and the coating machine main body.
, In order to suppress the waste~ul loss o~ the paint,
In an electrostatic multi-color coatiny apparatus ~or use in the coating of automobiles, -the color of paint i.5 often changed from one to another and cleaniny for t,he inside Oe the coatiny apparatus i5 necessary on every color change for avoidiny unde.sired mixing of colors. In such a case, it has been required to minimize the waste~'ul loss o~ paints upon color-chanye and to reduce the cleaniny time upon color change as short as possible. In order to satisfy the Eoreyoiny requirements, it may be considered to situate a color-change device for selectively supplying paints o~ a multiplicity of colors near the electrostatic coating machine thereby shorten the ~.
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paint supply channe], connected between the coating machlne and the color-change device 80 that the residual amount o~
paint in the paint supply channel is reduced.
However, i~ the color change device is disposed near the coating machine, an excess load is undesirably applled to a reciprocator adapted to drlve the coating machine ln accordance with a predetermined coating pattern. In view Or the above, the use Or a considerably long paint supply channel has been inevitable.
Then, ~or shortening the cleaning time upon color-change, cleaning air and cleaning thinner at high pressure have been supplied ~rom the color-change device to the paint supply channel to thereby rapidly clean the inside Or the paint supply channel and the atomizing cup.
However, such a system involves another problem that the waste~ul loss Or the paint i8 inevitable and a great amount o~ paint and cleaning thinner are violently blown out rrom the cup o~ the electrostatic coating machine because a great amount of the cleaning thinner is supplied in a short time to the inside of the paint supply channel.
They are overrlown rrom and scattered around to the outside the shroud disposed at the periphery o~ the cup o~ the coating machine ~or recovering the discharged liquid, to contaminate the peripheral equipments and the coating machine main body.
, In order to suppress the waste~ul loss o~ the paint,
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, it has been proposed such a device i.n whlch a second color~change device smaller in size than the above-mentioned color-change device is disposed near the electrostatic coatlng machine to shorten the palnt supply channel connected between the second color-change device and the coating machine. Those paints used frequently, ~or example, whlte or red pa:Lnt is selectively ~upplied rrom the second color-change device. For the cleaning upon color-change, cleaning air and cleaning thinner are alternately supplled ~rom the second color-change device to the paint supply channel, the paint hose and the coatlng mach:Lne.
However, also in this case, if the cleanlng alr and the cleaning thlnner at high pressure are supplied from the second color-change device, a great amount Or paint i8 Jetted out rrom the cup Or the electrostatic coating machine, over~lown ~rom and scattered around to the outside o~ the shroud to contaminate the peripheral equipments or the coating machine main body, although the cleaning time can be shortened. Further, ir the cleaning air and the cleaning thlnner are supplied at low pressure ~rom the second color change device in order to avold this drawback, contamination occurs or paint color remains to the inside o~ a mani~old disposed to the color-change device and havlng color-change valves, as well as to the inslde Or the palnt suppl~ channel connected therewith, whereby mixing
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, it has been proposed such a device i.n whlch a second color~change device smaller in size than the above-mentioned color-change device is disposed near the electrostatic coatlng machine to shorten the palnt supply channel connected between the second color-change device and the coating machine. Those paints used frequently, ~or example, whlte or red pa:Lnt is selectively ~upplied rrom the second color-change device. For the cleaning upon color-change, cleaning air and cleaning thinner are alternately supplled ~rom the second color-change device to the paint supply channel, the paint hose and the coatlng mach:Lne.
However, also in this case, if the cleanlng alr and the cleaning thlnner at high pressure are supplied from the second color-change device, a great amount Or paint i8 Jetted out rrom the cup Or the electrostatic coating machine, over~lown ~rom and scattered around to the outside o~ the shroud to contaminate the peripheral equipments or the coating machine main body, although the cleaning time can be shortened. Further, ir the cleaning air and the cleaning thlnner are supplied at low pressure ~rom the second color change device in order to avold this drawback, contamination occurs or paint color remains to the inside o~ a mani~old disposed to the color-change device and havlng color-change valves, as well as to the inslde Or the palnt suppl~ channel connected therewith, whereby mixing
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~, ' ~ ~:8~L36 oF colors Is resulted between palnts used before and after the color-change to Impalr the qualIty oF coatlng products.
-rhe present Inventlon provldes a cleanln0 devlce upon color-change In an electrostatlc multl-color coatlng machlne whlch can reduce the amount of palnt remalnlng In the palnt sup-ply channel by shortenlng the palnt supply channel for supplyln~
a palnt oF speclflc color thereby preventlng the wasteful loss of , the palnt; shorten the tlme requlred for cleanlng UPon color~
change by cleanlng the palnt supply channel connected wlth the color-change devlce and a paln~ hose conn~cted to the coatln0 machlne slmultaneously and separately; prevent palnts of dlffer-ent colors from mlxln~ wlth each other, and whlch Is ~ree from the drawback that ~he palnt blown oUt from the atomlzlng cup of the electrostatlc coatlng machlne Is overflown from and scattered around to the outslde of a shroud by the supply of an alr at low pressUre and a cleanlng thlnner at low pressure to the Palnt hose.
Accordlng to the present Inventlon there Is provlded a clean~ng devlce upcn color-change In an electrostatlc multl-color electrostatlc coatlng apparatus comprlsIng: a flrst color-change devlce comprlsIng a flrst manlfold Includlng valves for supplyIng respectlve palnts of dlfferent colors, a cleanlng alr and a cleanlng thlnner selectlvely through a flrst palnt supply chan-nel; a second color-change devlce smaller In slze than sald flrst color-change devlce, dlsposed near the electrostatlc coatlng machlne and comprlslng a second manlfold Includlng valves for supplylng respectlve Palnts of dlfferent colors, a cleanlng alr and a cleanlng thlnner selectlvely through a second palnt supply channel; and a valve mechanIsm dIsposed near sald electrostatlc coatlng machlne for supplylng a palnt suppl7ed from sald Flrst color-change devlce or sald second color-change devlce selec-tlvely through sald flrst palnt supply channel or sald second 3~ palnt supply channel to an electrostatlc coatlng machlne by way of a common palnt hose, whereln sald valve mechanlsm comprlses a ~ ~ .
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~LX~3S~36 thlrd manlfoid In communlcatlon wlth sald hose and Includln~ a fIrst swltchlng valve havln~ two exlt channels selectlYely con-nectable to sald flrst palnt supply channel, a second swltchlng valve havlng two exlt channels selectlvely connectable to sald second palnt supply channel, and a low pressure alr supply valve and a low pressure thlnner supply valve, In whlch one of the exlt channels of sald flrst swltchln~ valve and one of the exlt chan-nels of sald second swltchln~ valve are connected by way of sald , thlrd manlfold to sald palnt hose, whlle the other oF the exlt channels of sald swltchlng valves are connected by ON-OFF valves to a llquld dlschar~e channel whlch leads to a llquld dlschar~e tank. Sultably, an eJector Is connected to the end of the llquld dlscharge channel adJacent the dlschar~e tank.
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'''`~''`~ ' ' ~8~136 According to this invention, since the first and the second paint supply channels connected with the fi.rst and the second color-change devices are respectively cleaned by the cleaniny air ancl the cleaning thinner supplied from the ~irst and the second color-change devices respect:ively, while the paint hose connected to the electrostatic coating machine is cleaned by the cleaning air at low pressure and the cleaniny thinner at low pressure supplied from the low pressure ai.r supply valve and the low pressure thinner supply valve, it i5 poss.ible to significantly shorten the cleaning time, avoid the contaminat.i.ons and remaining of paint color which have occurred so far, and prevent contaminations in the peripheral equipments and the electrostatic costiny machine main body due to the scattering of the paint from the atomizing cup of the coating machine to the outside of the shroud.
Advantageous features of this invention will now be described more in detail by way of its preferred embodiment with reference t.o the accompanying drawings, wherein Figure 1 is a system chart showing the schematic constitution ~or one embodiment of an electrostatic multi-color coating apparatus to which this invention is applied, and . . , "~' ~' .
Fiyure 2 is a time char-t for illustratincJ one embodiment of the cleanillg device accordiny to this invention.
Fig. 1 is a system chart showing the schematic constitution oE a cleaning device upon color-change in an electrostatic multi-color coatlng apparatus accordiny to this invention.
In the drawings, the cleaning device comprises an atomiziny cup or bell 1 of an electros-tatic coa-tiny machine which appli.ed with a high voltage and rotationally driven at a high speed (hereinafter simply reEerred to as a cup); a first color-chanye clevice 2 supplied with paints of a mul.tiplicity oE different colors from a plurality of paint supply sources (not illustrated), cleaning air and cleaning thi.nner; a second color-change device 3 which is smaller in ~ize than the first color-change device 2 and disposed near the cup 1 of the electrostatic coatiny machine and supplied with paints of at least one color, a cleaning air at high pressure and a cleaniny thinner at hi.gh pressure; and a valve mechanism 4 constituted with first and second switching valves 6 and 13, a low pressure air supply valve LE1, a low pressure thinner supply valve LS1, etc. attached to a manifold 7, all of which are described later more specifically.
A relatively long paint supply channel is disposed :
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~2~3S~36 ror supplylng a paint o~ a desired color selected rrom the first color change devlce 2 to the cup 1 o~ the electro-static coating machine and the channel 5 is connected to a Pirst switching valve 6 having exit channels ~or two ways.
The switching valve 6 i9 di.sposed to the mani~old 7, in which one o~ the exit channel.s is communicated by way o~ a liquid discharging ON-OFF valve 8 with a liquid discharge channel 10, which communicates by way o~ a liquid discharging ON-OFF valve 8 to a liquid discharge tank 9, while the other of the exit channels i8 connected by way o~ the mani~old 7 to the paint hose 11 connected to the cup 1.
A second supply channel 12 o~ a rather shorter length is disposed for supplying a paint selected b~ the second color-change device 3 to the cup 1 o~ the electrostatic coating machine, and the channel 12 is connected to a second switching valve 13 having exit channels ~or two : ways disposed to the mani~old 7.
The switching valve 13 is connected at one exit ~: channel thereo~ by way o~ a liquid discharging ON-OFF
valve 14 to a discharge liquid channel 15, which is ~urther communicated with a liquid discharge tank 9, while connected : at the other exit channel thereo~ by way o~ the mani~old 7 to the paint hose 11.
A low pressure air supply valve LEl for supplying a .-:
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cleanlng alr at low pressure and a low pressure thlnner supply valve LSI for supplylng a cleanlng thlnner at low pressure are dlsposed to one end of the manl~old 7~ whlch Is connected at Its the ot~ler end wlth the palnt hose t1.
In the fIrst color-change devlce 2, a plurallty of color-change valves CV1 - CV13 connected respectlvely to palnt supply sources for varlous dlfferent colors (not Illustrated), a low pressure alr supply valve LE2 and a hlgh pressure alr suPply valve ~IE2 and a hlgh pressure thlnner supply valve HS2 arc dls-posed to a manlfold 16 connected to the fIrst palnt supply chan-nel 5.
In the second color-change devlce 3, a plurallty of color-change valves for supplylng those palnts used Frequently such as a color-change valve CVw for supplylng whlte palnt and a color-change valve CVr Çor supplylng red Palnt, a low pressure alr supply valve LE3, a hlgh pressure alr supply valve HE~ and a hlgh pressure thlnner supply valve HS3 are dlsposed to a manlfold 17 connected to the second palnt supply channel 12.
In the drawlng, reference numeral 18 denotes a shroud for recoverlng the dlschar~ed liquld blown out from the cup 1.
The llquld dlscharge channel 15 from the ON-OFF valve 14 Is con-nected to the llquld dlscharge tank 9 by way of an eJector 19.The eJector Is a devlce usually called a Jet pump or an eJector which Is adapted to Jet fluld at hlgh speed and hl~h pressure tb ~ cause a low pressure area to which Is connected low pressure ; fluld that Is sucked In and dlscharged hydrodynamlcally wlth the Jet. The eJector 19 has a port a for Introduclng a high pressure alr stream for suc~lng llquld palnt from the channel 15 by the : sudden drop of pressure near the hlgh speed alr stream and a dls-charge port b for dlscharglng the resultlng air-P~lnt mlxture to the llquld discharge tank 9.
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1~513~
rrhe operation of the device ~Iccordiny to this invention haviny the schematic constitution as shown in Figure 1 will now be expla:ined speci:Eically also referring to the time chart shown in Figure 2.
Assuming such a case where a white paint or a red paint most fre~uently used as the coating color Eor car bodies is supp].ied to the color-change valve CVw or CVr of the second color-change device 3 disposed near the cup 1 of the electrostatic coating machine, when a car body, for example, of a white color is conveyed to the coatiny reyion, the l is applied with a high voltage and rot:ationally driven at a high speed at first.
Then, by opening the second switching valve 13 while closiny the first stitchiny valve 6, a flow path is established from the manifold 17 of the second color-change device 3 by way of the second paint supply channel 12, the second switching valve 13, the manifold 17 and the paint hose 11 to the cup 1.
The white paint is supplied through the thus formed flow path by opening the color-change valve CVw disposed to the second color-change device 3.
Coating is thus started in which the white paint is electrostatically atomized in and released from the cup 1 to apply electrostatic coating on the surface of the car body being conveyed.
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Just before the completion o~ the coating, by opening the low pressure alr supply valve LE3 while closing the color-change valve CVw, a cleaning alr at low pressure about at the sa~e level as that o~ the white paint having been supplied from the color-change valve CVw is sent by way o~ the manifold 17 to the inside o~ the second paint supply channel 12~
Thus, the white pain-t is electrostatically atomized ~rom the cup 1 continuously till the completion o~ the coating, so that it may be applied to the car body without leaving the not yet painted portion and most Or the residual paint which would otherwise remain in the ~low path i8 released under electrostatic atomization and can be used e~fectively with no loss.
When the coating has thus been completed, the low pressure air supply valve LE3 is closed. Simultaneously, the number o~ rotation ~or the cup 1 i8 reduced and the shroud 18 retractably arranged near the cup 1 is advanced so as to surround the cup 1. Then, after closing the second switching valve 13 and opening the liquid dis-charging ON-OFF valve 14, the high pressure air supply valve HE3 and the high pressure thinner supply valve HS3 disposed to the second color-change device 3 are opened alternately to discharge the white paint remaining in the manifold 17 o~ the second color-change device 3 and in the second paint supply channel 12 by way o~ the liquid dis-' 3~i charge channel 15 Into the 11quld dlscharge tank 9, whereby theInsldes of the manlfold 17 and the second palnt supply channel 12 are cleaned rapldly.
Slmultaneously, the low pressure alr supply valve LE1 and the low pressure thlnner supply valve LS1 are opened and closed alternately thereby supplylng an a ! r at low pressUre and a thlnner at low pressure to blow the whlte palnt remalnln~ Insldes , of the manlfold 7 and the palnt hose 11 out of the cup 1 of the coatlng machlne. The palnt thus blown out Is recovered In the : shroud 18 and the cleanlng operatlon Is thus completed.
Slnce the Insldes of the manlfold 17 of the second color~chan~e devlce 3 equlpped wlth the color-chan~e valves CVw, CVr, etc. and the Insldes of the palnt hose 11 and the cup 1 are cleaned slmultaneously, the tIme requlred for cleanlng can be shortened slgnlflcantly.
Partlcularly, If the resldual palnt or the llke In the second palnt supply channel 12 I s d I scharged to the llqul d dIs-charge tank 9 by supplylng the cleanlng alr at hl~h pressure and the cleanlng thlnner at hl~h pressure from the second color-- change devlce 3 together wlth slmultaneous actuatln~ of the eJec-tor 19 connected to the end of the llquld dlscharge channel 15, the cleanlng tlme can further be shortened, as well as the Inslde : of the manlfold 17 and the Inslde of the second palnt supply : channel 12 can be cleaned thoroughly to avold the contamlnatlon or remalning of the palnt color, ; 30 , '-35~ 6 whereby the mixing Or colors can be prevented to improve th~ coating quallty.
In addition, since the paint and the paint-containing cleaning thinner are blown out o~ the cup 1 under a reduced pressure, there is no worry that they are scattered externally out o~ the shroud 18 to contaminate the peripheral equipments or the electrostatic coating machine main body.
Subsequent to the coating Or the white color rollo~ed by cleaning, when it is intended to change color Or paint from whi-te to that Or a paint (for example, blue) supplied to -the color-change valve CVl, for instance, of the rirst color-change devlce 2, the ~irst switching ~alve 6 is opened and the second switching valve 13 is closed to ; establish a flow path from the manirold 16 Or th~ rirst color-change device 2 by way Or the first paint supply channel 5, the rirst switching valve 6, the manirold 7 and the paint hose 11 to the cup 1. Then, the number o~
rotation for the cup 1 is increased to a predetermined Ievel arter retracting the shroud 18 rrom the cup 1.
Then, the color~change valve CVl is opened and the blue paint supplied thereto is sent through the above~
mentioned ~low path to the cup 1 to start the coating and apply electrostatic coating to a succeeding car body now being conveyed.
Just berore the completion Or the coating, the cleaning air at low pressure about at the same level as :........ , :
~Z8~36 that Or the paint supplied ~rom the color-change valve CVl i8 sent to the inside of the flrst palnt ~upply channel 5 by closing the color-change valve CVl and opening the low pres~ure air supply valve LE2.
In this way, the paint in the firs~ paint supply channel 5 i9 supplied to and electrostatically atomized i~
the cup 1 conti.nuously till the completion of the coating, so that most of the paint which would otherwise remain usually in the first paint supply channel 5 is electro-statically atomized ~rom the cup 1 and can be used e~ec-tively with no loss.
When the coating has thus been completed, the low pressure air supply valve LE2 is closed, the number of rotation for the cup 1 is reduced and the shroud 18 is advanced so as to surround the cup 1.
Then, after closing thc first switching valve 6 and opening the liquid discharging ON-OFF valve 8, the high pressure air supply valve HE2 and the high pressure thinner supply valve HS2 disposed to the first color-change device 2 are alternately opened to discharge the paint remaining to the inside of the first paint supply channel 5 by way of the liquid discharge channel 10 to the liquid discharge tank 9, by which the inside of the mani-fold 16 and the inside of the first paint supply channel 5 are cleaned rapidly. Also in-this case, after closing the ~irst s~itching valve 6, the low pressure air supply valve .
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LEl and the low pressure thinner supply valve LSl disposed to the manifold 7 of the valve mechanism 4 are opened alternately to supply the cleanlng air at low pressure and the cleaning thinner at low pressure through the manifold 7 to the inside of the paint hose 11, by which the inside of the paint hose 11 and the inside of the cup 1 are cleaned.
Accordingly, since the lnside of the relatively long first paint supply channel 5 i8 cleaned rapldly by the cleanlng air at hLgh pressure and the cleaning thinner at high pressure supplied froM the first color-change device 2 and, simultaneously, the inside of the short paint hose 11 and the inside o~ the cup 1 are cleaned by the cleaning air at low pressure and the cleaning thinner at low pressure supplied respectively from the low pressure air supply valve LEl and the low pressure thinner supply valve LSl disposed separately, the cleaning time upon color-change can significantly be shortened. In addition, since the paint and the paint-containing thinner are blown out under reduced pressure from the cup 1 also in this case, there is no worry that they are scattered around to the outside of the shroud 1~ to thereby contaminate the peripheral equipments or the electrostatic coating machine main body.
As has been described above according to this embodiment, since a palnt of a particular color used frequently is supplled from the second color-change device ::
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3 dispo6ed near the head 1 of the Hlectrostatic coating machine by way of the rather short second paint supply channel 12 and the paint hose 11 to the cup 1, the required amount of the paint can be economized.
In addition, since the paint in the relatively long first paint supply channel 5 connected between the first color~change device 2 and the first switching valve 6, a~
well as the paint in the second paint supply channel 12 connected between -the second color-change device 3 and the second switching valve 13 are supplied by way of ~he cleanlng air at low pressure to the cup 1 be~ore the completion of the coating, the residual amount Or the paint remaining in the first and the second paint supply channels 5 and 12 is extremely small and, therefore, the amount of the paint discharged as the liquid wastes at the completion of the coating can be minimized to eliminate the wasteful loss of the paint, as well as improve the cleaning ef~ect.
Further, in the case Or cleaning upon color-change of paints that have been supplied from the rirst and the ~: second color-change devices 2, 3, since the insides of the first and the second paint supply channels 5 and 12 are cleaned rapidly by the cleaning air at high pressure and the cleaning thinner at hlgh pressure supplied ~rom the n ~irst and the second color-change devices 2 and 3 respec-~ tively, as we}l as the inside of the paint hase 11 is ,~
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~' '-, ` ~' , 12~ 36 cleaned by th~ cleaning air at low pressure and the cleaning thinner at low pressure supplied from the low pres~ure air supply valve LEl and the low pressure thinner supply valve LSl Or the valve mechanism 4 disposed near the electrostatic coating machine, the cleaning time can signiricantly be shortened.
In addition, since the inside of the pain-t hose 11 and that of the cup 1 are cleanecl by the cleaning Qlr at low pressure Qnd -the cleaning thinner at low pressure, there i9 no worry that the palnt~ and the like remaining in the paint hose 11 are scat-tered around to the outside Or the shroud 18 to col~taminate the peripheral equipments and the electrostatic coating machine main body when they are blown out Or the cup 1 as experienced æo far.
According to this i~vention1 as has been described above, since the first and the second paint supply channels connected to the first and the second color-change devices are cleaned with the cleaning air and the cleaning thinner supplied from the first and the second color-change devices respectively, as well as the inside Or the paint hose connected~to the electrostatic coating machine is cleaned by the cleaning air at low pressure and the cleaning thinner at low pressure sent from the low pressure air supply valve and the low pressure thinner supply valve, the cleaning time can significantly be shortened, this invention can provide excellene effects capable o~ avoiding .
12 ~3 5136 the contamination or remaining Or paint color in th~
manifold o~ the color-change device equipped with the color-change valves and the paint supply channels, as well as being free ~rom the contamination of the peripheral equipments and the electrostatic coating machine main body whlch would otherwi~e cau~ed by the pain~ ~cattered around ~rom the cup Or the coa~:lng machine to the out~ide o~ the shroud.
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~, ' ~ ~:8~L36 oF colors Is resulted between palnts used before and after the color-change to Impalr the qualIty oF coatlng products.
-rhe present Inventlon provldes a cleanln0 devlce upon color-change In an electrostatlc multl-color coatlng machlne whlch can reduce the amount of palnt remalnlng In the palnt sup-ply channel by shortenlng the palnt supply channel for supplyln~
a palnt oF speclflc color thereby preventlng the wasteful loss of , the palnt; shorten the tlme requlred for cleanlng UPon color~
change by cleanlng the palnt supply channel connected wlth the color-change devlce and a paln~ hose conn~cted to the coatln0 machlne slmultaneously and separately; prevent palnts of dlffer-ent colors from mlxln~ wlth each other, and whlch Is ~ree from the drawback that ~he palnt blown oUt from the atomlzlng cup of the electrostatlc coatlng machlne Is overflown from and scattered around to the outslde of a shroud by the supply of an alr at low pressUre and a cleanlng thlnner at low pressure to the Palnt hose.
Accordlng to the present Inventlon there Is provlded a clean~ng devlce upcn color-change In an electrostatlc multl-color electrostatlc coatlng apparatus comprlsIng: a flrst color-change devlce comprlsIng a flrst manlfold Includlng valves for supplyIng respectlve palnts of dlfferent colors, a cleanlng alr and a cleanlng thlnner selectlvely through a flrst palnt supply chan-nel; a second color-change devlce smaller In slze than sald flrst color-change devlce, dlsposed near the electrostatlc coatlng machlne and comprlslng a second manlfold Includlng valves for supplylng respectlve Palnts of dlfferent colors, a cleanlng alr and a cleanlng thlnner selectlvely through a second palnt supply channel; and a valve mechanIsm dIsposed near sald electrostatlc coatlng machlne for supplylng a palnt suppl7ed from sald Flrst color-change devlce or sald second color-change devlce selec-tlvely through sald flrst palnt supply channel or sald second 3~ palnt supply channel to an electrostatlc coatlng machlne by way of a common palnt hose, whereln sald valve mechanlsm comprlses a ~ ~ .
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~LX~3S~36 thlrd manlfoid In communlcatlon wlth sald hose and Includln~ a fIrst swltchlng valve havln~ two exlt channels selectlYely con-nectable to sald flrst palnt supply channel, a second swltchlng valve havlng two exlt channels selectlvely connectable to sald second palnt supply channel, and a low pressure alr supply valve and a low pressure thlnner supply valve, In whlch one of the exlt channels of sald flrst swltchln~ valve and one of the exlt chan-nels of sald second swltchln~ valve are connected by way of sald , thlrd manlfold to sald palnt hose, whlle the other oF the exlt channels of sald swltchlng valves are connected by ON-OFF valves to a llquld dlschar~e channel whlch leads to a llquld dlschar~e tank. Sultably, an eJector Is connected to the end of the llquld dlscharge channel adJacent the dlschar~e tank.
3~
'''`~''`~ ' ' ~8~136 According to this invention, since the first and the second paint supply channels connected with the fi.rst and the second color-change devices are respectively cleaned by the cleaniny air ancl the cleaning thinner supplied from the ~irst and the second color-change devices respect:ively, while the paint hose connected to the electrostatic coating machine is cleaned by the cleaning air at low pressure and the cleaniny thinner at low pressure supplied from the low pressure ai.r supply valve and the low pressure thinner supply valve, it i5 poss.ible to significantly shorten the cleaning time, avoid the contaminat.i.ons and remaining of paint color which have occurred so far, and prevent contaminations in the peripheral equipments and the electrostatic costiny machine main body due to the scattering of the paint from the atomizing cup of the coating machine to the outside of the shroud.
Advantageous features of this invention will now be described more in detail by way of its preferred embodiment with reference t.o the accompanying drawings, wherein Figure 1 is a system chart showing the schematic constitution ~or one embodiment of an electrostatic multi-color coating apparatus to which this invention is applied, and . . , "~' ~' .
Fiyure 2 is a time char-t for illustratincJ one embodiment of the cleanillg device accordiny to this invention.
Fig. 1 is a system chart showing the schematic constitution oE a cleaning device upon color-change in an electrostatic multi-color coatlng apparatus accordiny to this invention.
In the drawings, the cleaning device comprises an atomiziny cup or bell 1 of an electros-tatic coa-tiny machine which appli.ed with a high voltage and rotationally driven at a high speed (hereinafter simply reEerred to as a cup); a first color-chanye clevice 2 supplied with paints of a mul.tiplicity oE different colors from a plurality of paint supply sources (not illustrated), cleaning air and cleaning thi.nner; a second color-change device 3 which is smaller in ~ize than the first color-change device 2 and disposed near the cup 1 of the electrostatic coatiny machine and supplied with paints of at least one color, a cleaning air at high pressure and a cleaniny thinner at hi.gh pressure; and a valve mechanism 4 constituted with first and second switching valves 6 and 13, a low pressure air supply valve LE1, a low pressure thinner supply valve LS1, etc. attached to a manifold 7, all of which are described later more specifically.
A relatively long paint supply channel is disposed :
:
~2~3S~36 ror supplylng a paint o~ a desired color selected rrom the first color change devlce 2 to the cup 1 o~ the electro-static coating machine and the channel 5 is connected to a Pirst switching valve 6 having exit channels ~or two ways.
The switching valve 6 i9 di.sposed to the mani~old 7, in which one o~ the exit channel.s is communicated by way o~ a liquid discharging ON-OFF valve 8 with a liquid discharge channel 10, which communicates by way o~ a liquid discharging ON-OFF valve 8 to a liquid discharge tank 9, while the other of the exit channels i8 connected by way o~ the mani~old 7 to the paint hose 11 connected to the cup 1.
A second supply channel 12 o~ a rather shorter length is disposed for supplying a paint selected b~ the second color-change device 3 to the cup 1 o~ the electrostatic coating machine, and the channel 12 is connected to a second switching valve 13 having exit channels ~or two : ways disposed to the mani~old 7.
The switching valve 13 is connected at one exit ~: channel thereo~ by way o~ a liquid discharging ON-OFF
valve 14 to a discharge liquid channel 15, which is ~urther communicated with a liquid discharge tank 9, while connected : at the other exit channel thereo~ by way o~ the mani~old 7 to the paint hose 11.
A low pressure air supply valve LEl for supplying a .-:
: - 8 . ' .
- . :
~ -.
~ll.,f~8~ 3~
cleanlng alr at low pressure and a low pressure thlnner supply valve LSI for supplylng a cleanlng thlnner at low pressure are dlsposed to one end of the manl~old 7~ whlch Is connected at Its the ot~ler end wlth the palnt hose t1.
In the fIrst color-change devlce 2, a plurallty of color-change valves CV1 - CV13 connected respectlvely to palnt supply sources for varlous dlfferent colors (not Illustrated), a low pressure alr supply valve LE2 and a hlgh pressure alr suPply valve ~IE2 and a hlgh pressure thlnner supply valve HS2 arc dls-posed to a manlfold 16 connected to the fIrst palnt supply chan-nel 5.
In the second color-change devlce 3, a plurallty of color-change valves for supplylng those palnts used Frequently such as a color-change valve CVw for supplylng whlte palnt and a color-change valve CVr Çor supplylng red Palnt, a low pressure alr supply valve LE3, a hlgh pressure alr supply valve HE~ and a hlgh pressure thlnner supply valve HS3 are dlsposed to a manlfold 17 connected to the second palnt supply channel 12.
In the drawlng, reference numeral 18 denotes a shroud for recoverlng the dlschar~ed liquld blown out from the cup 1.
The llquld dlscharge channel 15 from the ON-OFF valve 14 Is con-nected to the llquld dlscharge tank 9 by way of an eJector 19.The eJector Is a devlce usually called a Jet pump or an eJector which Is adapted to Jet fluld at hlgh speed and hl~h pressure tb ~ cause a low pressure area to which Is connected low pressure ; fluld that Is sucked In and dlscharged hydrodynamlcally wlth the Jet. The eJector 19 has a port a for Introduclng a high pressure alr stream for suc~lng llquld palnt from the channel 15 by the : sudden drop of pressure near the hlgh speed alr stream and a dls-charge port b for dlscharglng the resultlng air-P~lnt mlxture to the llquld discharge tank 9.
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1~513~
rrhe operation of the device ~Iccordiny to this invention haviny the schematic constitution as shown in Figure 1 will now be expla:ined speci:Eically also referring to the time chart shown in Figure 2.
Assuming such a case where a white paint or a red paint most fre~uently used as the coating color Eor car bodies is supp].ied to the color-change valve CVw or CVr of the second color-change device 3 disposed near the cup 1 of the electrostatic coating machine, when a car body, for example, of a white color is conveyed to the coatiny reyion, the l is applied with a high voltage and rot:ationally driven at a high speed at first.
Then, by opening the second switching valve 13 while closiny the first stitchiny valve 6, a flow path is established from the manifold 17 of the second color-change device 3 by way of the second paint supply channel 12, the second switching valve 13, the manifold 17 and the paint hose 11 to the cup 1.
The white paint is supplied through the thus formed flow path by opening the color-change valve CVw disposed to the second color-change device 3.
Coating is thus started in which the white paint is electrostatically atomized in and released from the cup 1 to apply electrostatic coating on the surface of the car body being conveyed.
: . .
:
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~ ~ ~ 5 ~3 ~
Just before the completion o~ the coating, by opening the low pressure alr supply valve LE3 while closing the color-change valve CVw, a cleaning alr at low pressure about at the sa~e level as that o~ the white paint having been supplied from the color-change valve CVw is sent by way o~ the manifold 17 to the inside o~ the second paint supply channel 12~
Thus, the white pain-t is electrostatically atomized ~rom the cup 1 continuously till the completion o~ the coating, so that it may be applied to the car body without leaving the not yet painted portion and most Or the residual paint which would otherwise remain in the ~low path i8 released under electrostatic atomization and can be used e~fectively with no loss.
When the coating has thus been completed, the low pressure air supply valve LE3 is closed. Simultaneously, the number o~ rotation ~or the cup 1 i8 reduced and the shroud 18 retractably arranged near the cup 1 is advanced so as to surround the cup 1. Then, after closing the second switching valve 13 and opening the liquid dis-charging ON-OFF valve 14, the high pressure air supply valve HE3 and the high pressure thinner supply valve HS3 disposed to the second color-change device 3 are opened alternately to discharge the white paint remaining in the manifold 17 o~ the second color-change device 3 and in the second paint supply channel 12 by way o~ the liquid dis-' 3~i charge channel 15 Into the 11quld dlscharge tank 9, whereby theInsldes of the manlfold 17 and the second palnt supply channel 12 are cleaned rapldly.
Slmultaneously, the low pressure alr supply valve LE1 and the low pressure thlnner supply valve LS1 are opened and closed alternately thereby supplylng an a ! r at low pressUre and a thlnner at low pressure to blow the whlte palnt remalnln~ Insldes , of the manlfold 7 and the palnt hose 11 out of the cup 1 of the coatlng machlne. The palnt thus blown out Is recovered In the : shroud 18 and the cleanlng operatlon Is thus completed.
Slnce the Insldes of the manlfold 17 of the second color~chan~e devlce 3 equlpped wlth the color-chan~e valves CVw, CVr, etc. and the Insldes of the palnt hose 11 and the cup 1 are cleaned slmultaneously, the tIme requlred for cleanlng can be shortened slgnlflcantly.
Partlcularly, If the resldual palnt or the llke In the second palnt supply channel 12 I s d I scharged to the llqul d dIs-charge tank 9 by supplylng the cleanlng alr at hl~h pressure and the cleanlng thlnner at hl~h pressure from the second color-- change devlce 3 together wlth slmultaneous actuatln~ of the eJec-tor 19 connected to the end of the llquld dlscharge channel 15, the cleanlng tlme can further be shortened, as well as the Inslde : of the manlfold 17 and the Inslde of the second palnt supply : channel 12 can be cleaned thoroughly to avold the contamlnatlon or remalning of the palnt color, ; 30 , '-35~ 6 whereby the mixing Or colors can be prevented to improve th~ coating quallty.
In addition, since the paint and the paint-containing cleaning thinner are blown out o~ the cup 1 under a reduced pressure, there is no worry that they are scattered externally out o~ the shroud 18 to contaminate the peripheral equipments or the electrostatic coating machine main body.
Subsequent to the coating Or the white color rollo~ed by cleaning, when it is intended to change color Or paint from whi-te to that Or a paint (for example, blue) supplied to -the color-change valve CVl, for instance, of the rirst color-change devlce 2, the ~irst switching ~alve 6 is opened and the second switching valve 13 is closed to ; establish a flow path from the manirold 16 Or th~ rirst color-change device 2 by way Or the first paint supply channel 5, the rirst switching valve 6, the manirold 7 and the paint hose 11 to the cup 1. Then, the number o~
rotation for the cup 1 is increased to a predetermined Ievel arter retracting the shroud 18 rrom the cup 1.
Then, the color~change valve CVl is opened and the blue paint supplied thereto is sent through the above~
mentioned ~low path to the cup 1 to start the coating and apply electrostatic coating to a succeeding car body now being conveyed.
Just berore the completion Or the coating, the cleaning air at low pressure about at the same level as :........ , :
~Z8~36 that Or the paint supplied ~rom the color-change valve CVl i8 sent to the inside of the flrst palnt ~upply channel 5 by closing the color-change valve CVl and opening the low pres~ure air supply valve LE2.
In this way, the paint in the firs~ paint supply channel 5 i9 supplied to and electrostatically atomized i~
the cup 1 conti.nuously till the completion of the coating, so that most of the paint which would otherwise remain usually in the first paint supply channel 5 is electro-statically atomized ~rom the cup 1 and can be used e~ec-tively with no loss.
When the coating has thus been completed, the low pressure air supply valve LE2 is closed, the number of rotation for the cup 1 is reduced and the shroud 18 is advanced so as to surround the cup 1.
Then, after closing thc first switching valve 6 and opening the liquid discharging ON-OFF valve 8, the high pressure air supply valve HE2 and the high pressure thinner supply valve HS2 disposed to the first color-change device 2 are alternately opened to discharge the paint remaining to the inside of the first paint supply channel 5 by way of the liquid discharge channel 10 to the liquid discharge tank 9, by which the inside of the mani-fold 16 and the inside of the first paint supply channel 5 are cleaned rapidly. Also in-this case, after closing the ~irst s~itching valve 6, the low pressure air supply valve .
, . . ' ' .
~28~3~;
LEl and the low pressure thinner supply valve LSl disposed to the manifold 7 of the valve mechanism 4 are opened alternately to supply the cleanlng air at low pressure and the cleaning thinner at low pressure through the manifold 7 to the inside of the paint hose 11, by which the inside of the paint hose 11 and the inside of the cup 1 are cleaned.
Accordingly, since the lnside of the relatively long first paint supply channel 5 i8 cleaned rapldly by the cleanlng air at hLgh pressure and the cleaning thinner at high pressure supplied froM the first color-change device 2 and, simultaneously, the inside of the short paint hose 11 and the inside o~ the cup 1 are cleaned by the cleaning air at low pressure and the cleaning thinner at low pressure supplied respectively from the low pressure air supply valve LEl and the low pressure thinner supply valve LSl disposed separately, the cleaning time upon color-change can significantly be shortened. In addition, since the paint and the paint-containing thinner are blown out under reduced pressure from the cup 1 also in this case, there is no worry that they are scattered around to the outside of the shroud 1~ to thereby contaminate the peripheral equipments or the electrostatic coating machine main body.
As has been described above according to this embodiment, since a palnt of a particular color used frequently is supplled from the second color-change device ::
~2~s~a~
3 dispo6ed near the head 1 of the Hlectrostatic coating machine by way of the rather short second paint supply channel 12 and the paint hose 11 to the cup 1, the required amount of the paint can be economized.
In addition, since the paint in the relatively long first paint supply channel 5 connected between the first color~change device 2 and the first switching valve 6, a~
well as the paint in the second paint supply channel 12 connected between -the second color-change device 3 and the second switching valve 13 are supplied by way of ~he cleanlng air at low pressure to the cup 1 be~ore the completion of the coating, the residual amount Or the paint remaining in the first and the second paint supply channels 5 and 12 is extremely small and, therefore, the amount of the paint discharged as the liquid wastes at the completion of the coating can be minimized to eliminate the wasteful loss of the paint, as well as improve the cleaning ef~ect.
Further, in the case Or cleaning upon color-change of paints that have been supplied from the rirst and the ~: second color-change devices 2, 3, since the insides of the first and the second paint supply channels 5 and 12 are cleaned rapidly by the cleaning air at high pressure and the cleaning thinner at hlgh pressure supplied ~rom the n ~irst and the second color-change devices 2 and 3 respec-~ tively, as we}l as the inside of the paint hase 11 is ,~
~ - 16 , . . . : .
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,~ :
~' '-, ` ~' , 12~ 36 cleaned by th~ cleaning air at low pressure and the cleaning thinner at low pressure supplied from the low pres~ure air supply valve LEl and the low pressure thinner supply valve LSl Or the valve mechanism 4 disposed near the electrostatic coating machine, the cleaning time can signiricantly be shortened.
In addition, since the inside of the pain-t hose 11 and that of the cup 1 are cleanecl by the cleaning Qlr at low pressure Qnd -the cleaning thinner at low pressure, there i9 no worry that the palnt~ and the like remaining in the paint hose 11 are scat-tered around to the outside Or the shroud 18 to col~taminate the peripheral equipments and the electrostatic coating machine main body when they are blown out Or the cup 1 as experienced æo far.
According to this i~vention1 as has been described above, since the first and the second paint supply channels connected to the first and the second color-change devices are cleaned with the cleaning air and the cleaning thinner supplied from the first and the second color-change devices respectively, as well as the inside Or the paint hose connected~to the electrostatic coating machine is cleaned by the cleaning air at low pressure and the cleaning thinner at low pressure sent from the low pressure air supply valve and the low pressure thinner supply valve, the cleaning time can significantly be shortened, this invention can provide excellene effects capable o~ avoiding .
12 ~3 5136 the contamination or remaining Or paint color in th~
manifold o~ the color-change device equipped with the color-change valves and the paint supply channels, as well as being free ~rom the contamination of the peripheral equipments and the electrostatic coating machine main body whlch would otherwi~e cau~ed by the pain~ ~cattered around ~rom the cup Or the coa~:lng machine to the out~ide o~ the shroud.
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Claims (2)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A cleaning device upon color-change in an electrostatic multi-color electrostatic coating apparatus comprising: a first color change device comprising a first manifold including valves for supplying respective paints of different colors, a cleaning air, and a cleaning thinner selectively through a first paint supply channel; a second color-change device smaller in size than said first color-change device, disposed near the electrostatic coating machine and comprising a second manifold including valves for supplying respective paints of different colors, a cleaning air and a cleaning thinner selectively through a second paint supply channel; and a valve mechanism disposed near said electrostatic coating machine for supplying a paint supplied from said first color-change device or said second color-change device selectively through said first paint supply channel or said second paint supply channel to an electrostatic coating machine by way of a common paint hose, wherein said valve mechanism comprises a third manifold in communication with said hose including a first switching valve having two exit channels selectively connectable to said first pain supply channel, a second switching valve having two exit channels selectively connectable to said second paint supply channel, and a low pressure air supply valve and a low pressure thinner supply valve, in which one of the exit channels of said first switching valve and on of the exit channels of said second switching valve are connected by way of said third manifold to said paint hose, while the other of the exit channels of said switching valves are connected by ON-OFF valves to a liquid discharge channel which leads to a liquid discharge tank.
2. A cleaning device as defined in claim 1, wherein an ejector is connected to the end of the liquid discharge channel adjacent the discharge tank.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000500949A CA1285136C (en) | 1986-02-03 | 1986-02-03 | Cleaning device upon color-change in an electrostatic multi-color coating apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000500949A CA1285136C (en) | 1986-02-03 | 1986-02-03 | Cleaning device upon color-change in an electrostatic multi-color coating apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1285136C true CA1285136C (en) | 1991-06-25 |
Family
ID=4132404
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000500949A Expired - Fee Related CA1285136C (en) | 1986-02-03 | 1986-02-03 | Cleaning device upon color-change in an electrostatic multi-color coating apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1285136C (en) |
-
1986
- 1986-02-03 CA CA000500949A patent/CA1285136C/en not_active Expired - Fee Related
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