CA1253684A

CA1253684A - Spraying booth

Info

Publication number: CA1253684A
Application number: CA000478855A
Authority: CA
Inventors: Koji Morioka; Susumu Yoshida; Makoto Watanabe
Original assignee: Taikisha Ltd
Current assignee: Taikisha Ltd
Priority date: 1984-04-12
Filing date: 1985-04-11
Publication date: 1989-05-09
Also published as: GB2160639A; GB2160639B; KR870001594B1; KR850007388A; GB8509255D0

Abstract

Abstract of the Disclosure There is disclosed a spraying booth comprising a spraying chamber defining openings in a ceiling and in side walls thereof to receive ventilating gas incoming downwardly and sideways. The chamber further includes gas discharge openings through which the downward flows and sideways flows of the ventilating gas are forcibly discharged in confluent flows.

Description

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SPRAYING BOOTH

Background of the Invention This invention relates to a spraying booth for spraying paint on automobile bodies and casings for ; 5 household electric appliances, and more particularly to a ventilating system for the spraying booth.
A conventional ventilating system for the spraying booth noted above comprises air supply openings disposed over an entire ceiling area of the spraying booth for supplying filtered ventilating air into the booth down-wardly and in streamline flows. Discharge openings are arranged at intervals below a lattice floor of the booth for draining away through the entire area thereof the ventilating air together with entrained spray mist.
This construction is intended to promote effective ventilation by causing the ventilating air to advance downwardly in streamline flows through an entire area of the booth as much as possible so as to restrain any whirling flows that would blow the spray mist upwardly.
Such a construction was expected to facilitate maintenance of spraying machines and the like installed in the booth by reducing adhesion thereto of the spray mist, and to discharge the spray mist in a speedy manner to permit different ob~ects to be conveyed and painted efficiently with different colors without entailing discoloration _.
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of an object due to residual spray mist remaining in the booth after a preceding object is sprayed.
Through va~oustests, however, the above prior con-struction has been found ineffective. Thus, the venti-lating air caused to move downwardly in streamline flowsovex the entire area of the booth results in the spray mist blowing from above against any spraying machine and the like disposed sbout the object to be sprayed. This causes a great amount of spray mist to adhere to and accumulate on the spraying machines, which is totally contrary to the results this prior construction is inten-ded to achieve. The adhered and accumulated paint dries in the course of time and readily comes off the spraying machines due to vibrations thereof or by the action of the ventilating air flow. The paint then not only tends to adhere to sprayed surfaces of the object under treat-ment to become a cause of faulty coating but also disables the automatic spraying machines which are becoming in-creasingly sophisticated today. Pre~enting these prob-lems requires cleanina and other maintenance work to becarried out frequently and in a time-consuming manner, which also results in bad productivity~

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Summary of the Inventi.on The object of t~i.s inventi.on is to provide a rational improvement relating to a system, for producing venti-lating gas flows, which.retafns the function of dis-charging spray mist ~rom the ~ooth.speedily, effectivelyprevents the spray mist from adhering to the spraying machines around the object under treatment, and permits paint to be sprayed on the o~ject wlth increased efficiency.
In order to achieve the a~ove object, a spraying booth according to this invention comprl~es a spraying chamber, gas supply means for supplying ventilating gas tothespraying chamber, gas discharge means for di.scharging the venti-lating gas from t~e spraying cha~ber, downwardly directed opening means disposed in a ceiling of the spraying chamber for passing the ventilating gas from the ga~s supply means downwardlyinto thespraying chamber, sideways directed openingmeans forpassingtheventilating gas fromthe gassupply means sideways into thesprayingchamber,and gas discharge opening means disposedin a floorofthe spraying chamber to.communicate with the gas discharge means, the gas discharge opening -means being below an object under spraying treatment in the spraying chamber.
The construction defined above causes downward flows and sideways flows of the ventilating gas to join together and the resulting confluent flows to depart ,~

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:~S;3684 from the spraying chamber substa~tially in the same direction in which the confluent flows move within the spraying chamber, whereby substantially an entire amount of ventilating gas supply is directed toward the object under treatment.
Therefore, the spray mist floating in the spraying chamber is speedily removed from the spraying chamber by the smooth confluent flows of the ventilating gas toward the gas discharge opening means. Furthermore, since the downward flows of the ventilating gas are de-flected toward the object to be sprayed by the sideways flows,the spraying machines and the like disposed around the object are not exposed to downward flows of mist entrained in the gas, thereby avoiding adhesion of the paint to the spraying ~achines and the like.
Moreover, the ventilating gas flows converging on the object to be sprayed help sprayed paint to strike target surfaces of the object irrespective of the direction from which the paint is sprayed. The converging venti-lating gas flows are also effective in restraining super-fluous paint occurring during spraying from spreading in the booth interior in the form of spray mist. These functions combin~ to i~prove the paint coating efficiency.
Consequently, the spraying booth according to this ~ 25 invention permits different objects to be conveyed and : ~.
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lZ~ i34 painted with different colors as efficiently as in the prior art without entailing discoloration of an object due to residual spray mist in the booth resulting from spraying for a preceding object. The present spraying booth is also capable of substantially reducing the frequency of and time re~uired for cleaning and like maintenance work for the spraying machines and the like surrounding the object under treatment. Improved productivity has also been achieved by reducing the need for maintenance work during production times. In addition, the present spraying booth is effective in reducing the rate of faulty coating due to adhesion of dust to the object surfaces, while yet increasing the paint coating efficiency.
Thus, the spraying booth accoraing to this invention has excellent operability.
Other advantages of this invention will be apparent from the following description.

Brief Descr~ption of t1le Drawings ;; 20 Fig. l is a view in vertical section of a spraying booth according to a first e~bodi~ent of this invention, Fig. 2 is a schematic plan view of the spraying booth, :

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Fig. 3 is a partly broken away perspec-tive view of the spraying booth, Figs~ 4 through 6 are schematic views in vertical section showing partial modi~ications of the first embodiment, respectively, Figs 7 is a schematic view in vertical section of a prior art construction, Fig. 8 is a schematic plan view of the prior art construction, Fig. 9 is a view in vertical section of a second embodiment of this invention, Fig~ 10 is a schematic plan view of the second smbodimeDt, Fig. 11 is a partly broken away parspective view of the second embodiment~
Fig 12 is an enlarged plan view of a principal portion of a third embodiment of this invention, Fig. 13 is a section taken on line Y-Y in Fig. 12, Fig, 14 through 16 are enlarged plan views of the principal portion showing partial modifications of the third embodiment, respectively, and Fig. 17 is a schematic view of the first embodiment shown for compari~on purposes.

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Description of` the Preferred ~mbodiments A first embodiment of th.is invention will be described first with reference to Figs. 1 thro-ugh 3.
This booth comprises a spraying chamber 1 substantially of rectangular parallelpiped shape and including a front wall 2 and a back wall 3 defining entrance and exit openings 6, respectively, through which an object A
mounted on a carriage 4 is brought into and out of the spraying chamber 1 by a conveyor 5. The spraying chamber 1 houses automatic spraying machines 8 disposed on a lattice floor 7 and arranged on both sides of the conveyor 5 along its conveying direction, each of the spraying machines 8 comprising an articulated robot carrying a spray gun 8A, Each spraying machine 8 i9 automatically operable to spray paint according to a predetermined timetable on the object A stopped in position inside the chamber 1.
A ventilating system for the spraying chamber 1 includes a feed fan 9 and a dlscharge fan 10. Ventilating gas supplied to the chamber 1 is forcibly drawn by the discharge fan 10 entraining residual spray mist from the ~praying chamber 1 through the lattice floor 7.
- ~n exhaust route R extending from the spraying chamber 1 to the discharge fan 10 contains a first mist removing device 14 includig a pan 11 extending substantially o~er an entire area under the floor 7, 'l`he pan 11 receives ' ~ ..... : ,, , ~3~4 aggregates of paint descending from the -floor 7 without permitting the aggregates to adhere to the pan 11 by means of cleaning water W1 flowing down upper sur~aces thereof. A plurality of exhaust ducts l2 having slit-like openings in plan view are arranged parallel to oneanother to permit the exhaust gas to shoot downwardly without permitting the spray mist to adhere to inner walls of the ducts 12 by meaDS of the cleaning water Wl overflowing from the pan 11 and flowing down the inner peripheral walls. The first mist removing device 14 further includes a cleaning water vessel 13 disposed below the pan 11 and storing the cleaning water. The mist CODtaining gas shooting downwardly from the exhaust ducts 12 strikes against the surface of cleaning water stored in the vessel 13~ whereupon the spray mist is trapped in the water and separated from the ventilating gas by virtue of the difference in inertial mass between the spray mist and the ventilating gas.
The exhaust route R further contains a second mist removing device 16 downstream of the first mist removing device 14. The exhaust gas which has roughly been stripped of large diameter spray mist particles and aggregates of paint by the first mist removing device 14 is stripped of small diameter spray mist particles by the second mist removing device 16. ~lore particularly, the exhaust gas from the first mist removing device 14 is caused to flow ~Z~3t;~1~

conf`lllent:ly wi-th overflowing cleaning w~-ter i~ .t high velocity clown an S-shaped bending dllct 15, ~hereupon resulting centrifugal forces cause the small diameter spr~y nlist particles entrained in the gas to be trapped in the downflowing cleaning water W2 by virtue of tha difference in inertial mass between the mist particles and the gas as in the case of the first mist removing device 14.
The ventilating system for the spraying chamber 1 further includes downwardly directed gas inlet opsnings Sl arranged substantially over an entire area of a ceiling 17 The openings Sl permit the ventilating gas supplied under pressure to an upper chamber 18 by the feed fan 9 move through a filter 19 into the spraying chamber 1 in downwardly directed streamline flows Each of side walls 20A and 20B and front and back walls 2 and 3 of the spraying chamber 1 includes a perforated plate in a range of one third to two thirds from its bottom, preferably in its lower half. These perforated plates define sideways directed gas inlet openings S2-S5 for permitting the ventilating gas supplied under pressure to lateral chambers 21A and 21B and front and back chambers 21C and 21D to move through filters 22 into the spraying chamber 1 in sideways directed streamline flows Further, the slit-lilce openings of the exhaust ducts 12 constitute ventilating gas discharge openings 23 located g _ i : -.
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below the position .it which the object ~ stops for spraying treatment. Thus, this construc-tion causes tile ventilating gas introduced through the downwardly directed inlet openings Sl and the sideways direc-ted inlet openings S2-S5 to join together and the reslllting confluent flows to depart from the spraying chamber 1 through the gas discharge openings 23 below the object under treatment substantially in the same direction in which the confluent flows move within the spraying chamber 1. Substantially an entire amount of ventilatiDg gas supply is thereby directed to converge on the object A.
The residual spray mist in the spraying chamber 1 is speedily removed therefrom by the ventilating gas flows directed toward the object whilo improving paint coating efficiency. Since the downward flows of the ventilating gas are deflected toward the object A by the sideways flows, the spraying machines 8 around the object are not exposed to downward flows of mist containing gas thereby to avoid adhesion of paint to the spraying machines 8.
The described embodiment may be modified as follows:
As shown i Fig 4, the side walls ZOA and 20~ of the spraying chamber 1 may define gas inlet openings S2 and S3 o~er entire areas thereof, respectively, to introd~ce the ventilating gas i sideways flows. Thus, portions of the side walls 20A and 20~ defining the gas inlet openings S2 and S3 are variable ~s desired.

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f~S shown in ~ig 5, incli.ned gas inlet openings S6 and S7 Inay be provided between the downwardly directed gas inlet openings S1 in the ceiling 17 and the s:ideways directed gas inlet openings S2 and S3 in the side walls 20A and 20B, respectively, to introduce the ventilating gas in downwardly inclined flows.
The sideways directed gas lnlet openings S4 and S5 iD the front and back walls 2 and 3 may be dispensed with.
Fig 6 illustrates a further modified arrangement of means for introducing the ventilating gas in downwardly and sideways directed flows In this example the spraying chamber 1 has a dome-shaped wall defining ventilating gas inlet openings S directed toward a center portion of the dome shape, and gas discharge openings 23 arranged in the ; 15 center portion. Thus, the ventilating gas flows are converged on the object A positioned in the center portion ; above the gas discharge openings 23. In this invention, the sideways directed gas inlet openings S2-S7 ~eans those openings which introduce the ventilating gas in flows inclined up to 45 to the horizontal direction~ and ~ the downwardly directed gas inlet openings S1 mean those ; openings which introduce the ventilating gas in ~lows inclined up to 45 to the vertical direction Specific constructions of the downwardly directed gas inlet openings Sl and the sideways directed gas inlet openings S2-S7 are variable i n-any ways, and the construction :~ "

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of` the gas clischarge oper-ings 23 too is variable in many ways.
The ventilatin~ gas introduced through the downwardly directed gas inlet openings S1 and that introduced through the sideways directed gas inlet openings S2-S5 may be in a 1~ 2 or 2:1 ratio by amount or in such a ratio by velocity~ or in any other suitable ratios.
~ second embodiment of this invention will now be described with reference to Figs 9 through 11. Like components are affixed with like reference numerals, and detailed descriptions thereof are not repeated. Thus, the second embodiment will particularly be described with respect to guides 24 which constitute the characterizing feature of this embodiment As seen, the spraying chamber 1 includes the venti-lating gas discharge openings 23 constituted by the slit-like openings of the exhaust ducts 12 arranged below the position at which the object A stops for spraying treatment.
The side walls 20A and 20B of the chamber 1 define the sideways directed gas inlet openings S2 and S3, and plate-like guides 24 are provided behind and above bases 8B
of the spraying machines 8 These guides 24 extend from vertically intermediate positions of the sideways directed gas inlet openings S2 and S3 in the side walls 20A and 20B and include upper surfaces 24A inclined downwardly frorn the side walls 20A and 20~ toward the object ~.

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'rhis construction causes the ventilating gas in-trod~lced through the downwardly directed gas inlet openings S1 and the ventilating gas introduced through the sideways directed gas inlet openings S2-S5 to join together and the resulting confluent flows to depart from the chamber 1 through the gas discharge openings 23 below the object under treatment substantially in the same direction iD
which the confluent flows move within the spraying chamber 1, A substantially entire amount of ventilating gas supply is directed toward the object by action of the guides 24 to guide the ventilating gas flows.
The residual spray mist in the spraying chamber 1 is speedily removed therefrom and paint coating efficieDcy is promoted by the ventilating gas flows directed toward the object, The sideways flows of the ventilating gas which deflect the downward flows toward the object A, and and the guiding ac-tion of the guides 24 prevent mist containing gas from blowing downwardly against the bases 8B of the spraying machines 8 around the object A under treatment, Ventilating gas flows entering the spraying chamber 1 through portions of the sideways directed gas inlet openings S2 and S3 below the guides 24 act to prevent the mist containing gas from becomiDg caught under the guides 24. Thus, this construction is capable of positively protecting the bases 8B of the spraying machines 8 from e~dhesipo of the sprny mist due to the S36~4 mist containing gas blowing from above or beconling caught under the guides 24.
The specific construction of and mounting structure for the guides 24 having upper surfaces 24A inclined S downwardly toward the object under treatment may be varied in many ways. The upper surfaces 24A of the guides 24 may be declined at any suitable angles. Each of the guides 24 may have a gently beDding edge opposite the object A.
10The veDtilating gas introduced through the downwardly directed gas inlet openings Sl and that introduced through sideways directed gas inlet openings S2-S5 may be iD any suitable ratios by amount or velocity A third embodiment of this invention will be described 15hereinafter with reference to Figs. 12 through 17, Fig. 17 being a schematic view of the first embodiment shown for comparison purposes. As in the second embodiment, like components are affixed with like reference numerals, and detailed descriptions thereof will not be repeated. Thus, the third embodiment will particularly be described with respect to gas discharge openigs 23 which constitute the characterizing feature of this embodiment.
As shown in Fig. 12, the slit-like gas discharge openings 23 are arranged at suitable intervals in the direction of movement of the conveyor 5, the openings 23 having a transverse length substantially corresponding to .

~ 14 -~Z53~i84 a wiclth of the object A which in this instance is an automobile body. The discharge openings at respective ends of th~ row are located adjacent positions directly below longitudinal ends of the automobile body A when the latter is stopped in position for spraying treatment, and other 23 have longitudinal ends thereof located adjacent positions directly below lateral edges of the automobile body when the latter is stopped in position.
In other words, the gas discharge openings 23 are distributed circumferentially about and below outer peripheries of and also directly under the automobile body standing still. Each o~ the gas discharge openings 23 has a vertical width which is tapered downwardly when seen in the transverse direction of the conveyor.
According to the third embodiment as described above9 spray mist having intruded below the automobile body A
through gaps and the like therein is discharged speedily -~; and smoothly without allowing such spray mist to stagnate locally below the automobile body A since the ventilating gas is discharged not only through the positions directly ~; below the outer peripheries of the automobile body but ~` also through positions directly below the automobile body.
:' Since the discharge openings 23 are not located transversely outwardly of the positions directly below the outer peripheries of the automobile body A, the spray mist will no-t spread transversely outwardly of the automobile body 12S3~

to adhere to the spraying machines 8, Tlle third embodiment may be modified as follows:
,~s shown in Fig, 14, the gas discharge openings may each have a circular sh~pe (which may be square) in plan view, Such openings are arranged in positions directlv under the automobile body A standing still and in or adjacent positions directly under the outer peripheries thereof.
Referring to Fig. 15, the slit lilce gas discharge openings 23 may be arranged at suitable intervals trans-versely of the direction of movement of the conveyor so that each opening extends parallel to that direction, ;

These openings 23 are disposed below the automobile body A as are the foregoing e~amples.
Referring to Fig, 16, the slit-like gas discharge openings 23 may comprise a combination of those extending transversely of the direction of movement of the conveyor ~ and those extending parallel thereto. Here too~ the - openings are disposed blow the automobile body A as ara the preceding examples, Fig, 17 illustrates the position of the gas discharge openings 23 in the first embodiment which are directly under the object A standing still f`or spraying treatment, The gas discharge openings may be slightly displaced fron the illustrated position, llaving described the first to third embodinlents :

lZS36i5 4 and partial modificntions thereof, it will be appreciated that various other modifications may be made wi-thin the technical scope of this in~ention.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. A spraying booth comprising:
a spraying chamber (1) including, a ceiling (17) with a plurality of downwardly directed openings (S1) extending therethrough over the entire area thereof;
right and left lateral side walls (20A, 20B) each having first sideways directed openings (S2-S7) extending therethrough between one-third to two-thirds from the bottoms of the right and left lateral side walls, front and back walls (2, 3), a floor (7) having gas discharge openings (23), said gas discharge openings having a width substantially equal to a width of an object (A) undergoing spraying treatment in the spraying chamber (1) and being disposed below the object, said discharge openings (23) being constituted by a plurality of slits (12), gas supply means (9) connected to said downwardly and sideways directed openings (S1-S7), for supplying ventilating gas into the spraying chamber (1) and therethrough so that ventilating gas converges on the object (A) undergoing treatment and mist-free regions existing adjacent said sideways directed openings (S2-S7) formed through each of said right and left lateral side walls (20A, 20B), said mist-free regions having a substantially triangular cross-section with a base extending from the right and left lateral side walls, respectively, to the gas discharge openings (23) formed in the floor (7) and having a height corresponding to the height of the sideways directed openings (S2-S7); and gas discharge means (10) connected to said gas discharge openings (23) for receiving the gas discharged therethrough and for conducting the gas to a point remote from the spraying booth.

2. A spraying booth as claimed in claim 1 wherein the downwardly directed openings (S1) and sideways directed openings (S2-S7) permit the ventilating gas to enter the spraying chamber (1) substantially in streamline flows.

3. A spraying booth as claimed in claim 2 wherein the sideways directed openings (S2-S7) are arranged in opposing pairs.

4. A spraying booth as claimed in claim 2 wherein the sideways directed openings (S2-S7) are arranged substantially over an entire circumference of the object (A) under spraying treatment.

5. A spraying booth as claimed in claim 2 further comprising guide plate means (24) each extending from a vertically intermediate position of the sideways directed openings disposed in a lateral side wall (20A or 20B) of the spraying chamber (1) and including a downwardly inclined upper surface (24A).

6. A spraying booth as claimed in claim 2 wherein the gas discharge openings (23) are disposed in a position below the object (A) under spraying treatment and corresponding to outer peripheral edges of the object.

7. A spraying booth as claimed in claim 5 wherein the gas discharge openings (23) are disposed in a position below the object (A) under spraying treatment and corresponding to outer peripheral edges of the object.

8. A spraying booth as claimed in claim 2, 6 or 7 wherein the gas discharge openings (23) are disposed substantially right below the object (A) under spraying treatment.

9. A spraying booth as claimed in claim 2, 6 or 7 wherein the gas discharge openings (23) comprising the plurality of slits (12) are arranged at suitable intervals in positions below the object (A) under spraying treatment and corresponding to outer peripheral edges of the object (A).