AU427995B2 - Coating apparatus - Google Patents

Description

18,2 3 4 no The present invention relates to a method and to a

coating apparatus including coating devices used to deposit a

protective or decorative coating material upon an article having

one or more irregular surface contours. More particularly, the

present invention relates to a method and to a coating apparatus

including one or more coating devices displaceable to each of a

plurality of different positions during a coating cycle to there-

by facilitate the coating of an article having irregular surface

contours such as an automobile body.

In several coating apparatus, successive articles to

be coated are carried by a conveyor past the coating apparatus.

When the articles are in a coating zone, as determined by the

characteristics of the spray pattern or patterns emerging from

the coating devices of the coating apparatus, the articles are

coated by the particles of the spray. When operating the coating

apparatus, it is preferred that the distance between the nozzle,

extremity, edge and the like of the coating devices from which

the coating material is atomized and the surface of the article

being coated be maintained within specified limits. The distance

between the nozzle, extremity, edge and the like of the coating

devices is particularly important where the spray patterns

emerging from adjacent coating devices of the coating apparatus

are to be blended together on the article.

An article, such as a hand toy, having a relatively

limited surface area generally presents little, if any, coating

-problem. The same can be said of an article having a relatively

large but regular surface contour such as a refrigerator body.

However, when the articles have a relatively large surface area,

it is frequently necessary, in order to obtain a uniform coating

over the surface of the article, to move the coatingdevice or ,i '4 7995

18,2 3 4 no and the like of the coating device and the irregular surface

contours of the automobile bodies may result in a coating

material film on such surface contours which is not sufficiently

thick to accomplish its intended purpose of protection, decoration

or both. If the speed with which the coating device traverses or

crosses such irregular surface contours is slowed to obtain a

coating material film of the proper thickness to accomplish its

intended purpose, the spray patterns emerging from adjacent spray

coating devices may not blend properly due to, among other things,

the substantially continuously4= distance between the

nozzle, edge, extremity and the like of the coating device and

the surface contours being coated with coating material. A

tentative solution to the problems presented by the reciprocator

which displaces the coating device or devices only in one plane

is to position a vertically displaceable spray device on a suit-

able overhead carriage mechanism which moves with each automobile

body in the horizontal direction for a short distance. However,

the tentative solution proves to be unsatisfactory due to foreign

particles such as dirt, dust and the like which may be accumulated

upon the carriage and its cooperatively associated guide and be

released by the movement of the carriage during the coating cycle.

Such particles tend to fall or "float" into the coating zone and

come to rest on the automotive body thereby undermining the quality

of the coating and, at times, resulting in rejected bodies because of a lack of a quality coating.

The problems associated with coating automobile bodies

is more acute if the upper portions of adjacent automobile bodies

are separated by less distance than the lower portions of the

adjacent automobile bodies. For example, where a plurality of

adjacent spray devices are used, the spray patterns of the V-n.nt

18,234/70 spray devices may not blend properly resulting in a finish on

either the upper portion or the lower portion or both portions

of the automobile body which is undesirable.

It is, therefore, an object of the present invention

to provide a coating apparatus including means for moving a

coating device or devices across the irregular surface contours

of a substantially continuously moving series of articles such

as automobile bodies in such a manner as to provile adequate

time for coating such surface contours without m-terially alter-

ing the rate of movement of such articles. Another object of

the present invention is to provide a coating apparatus with

means for determinately aligning and maintaining a substantially

uniform distance between the nozzle, extremity, edge or the

like of the coating device or devices and the irregular surface

contour of the substantially continuously moving series of

articles. Yet another object of the present invention is to

provide vertically displaceable and pivotal back-to-back rows

of electrostatic spray coating devices which coat the front and

the rear surfaces of articles such as automobile bodies.

Generally speaking, the present invention relates to a

method and to a coating apparatus including either an electrosta-

tic or non-electrostatic coating device or devices for spray

coating an irregular surface contour or area such as the front

and rear surfaces of an automobile body. The apparatus includes

a conveyor for transporting a series of automobile bodies to be

coated with protective or decorative coating material through

a coating zone. Where electrostatic coating devices are used,

a high voltage direct current source is connected to the electro-

static coating devices. An electrical charge difference is pro- duced between the particles of coating material and an automobile

16, 234/70 body in the coating zone whereby the particles of coating material

are deposited upon the surface of the automobile body. A programmed member carries the electrostatic or non-electrostatic coating device

or devices as the case may be. The member moves the coatinq device or devices into the gap or spacing between successive automobile

bodies. The member displaces the coating device or devices across the irregular surface contours of the automobile body. Pivotal movement of the member assists in maintaining the coatinq device

or devices at a substantially constant distance from the irregular

surface contours of the automobile body and assists in aligning

the axis of the coating device or devices with respect to the

plane of the irreqular surface contour of the automobile body,

such as inwardly sloping surface contours of the front and the rear surface of the automobile body, so as to be substantially

perpendicular to such plane of the surface contours of the auto- mobile body when dispensing coating material toward the automo- bile body.

It is to be understood that the present invention is applicable to either an electrostatic or non-electrostatic coating device or devices which dispense or emit either liquid or non- liquid coating materials. Suitable liquid coating materials are paint lacquers, varnishes, enamels, and the like. Suitable non- liquid coatina materials are thermosetting powders such as epoxy resin and the like and thermoplastic powders such as polyvinyl- chloride, polypropylene, polyester, polyethylene and the like. For illustration only and not for limitation, the invention will be disclosed in conjunction with the use of electrostatic coating devices which emit a liquid coating material such as paint. In the drawing:

FIGURE 1 is a diagrammatic side view of a coating S. 4:279.95

L0. J .4/70 apparatus embodying the invention;

FIGURE 2 is a diagrammatic top view of the coating

apparatus of FIGURE 1 with components removed;

FIGURE 3 is a diagrammatic side view of the apparatus

used to move or displace the coating devices; and

FIGURE 4 is a diagrammatic illustration of the move-

ment of the coating devices shown in dotted lines.

Referring now to the several FIGURES o(if the drawing,

and in particular to FIGURES 1 and 2, a series of automobile

bodies 10 to be coated with a film of a suitahle protective or

decorative coating material are transported to a coating station

by any suitable means such as carriage means 11. The automobile bodies 10 are illustrated as being electrically grounded through

the carriage means 11. The automobile bodies are transported by a conveyor line which include tracks 12 and a conveyor chain 13.

The conveyor substantially continuously moves the automotive

bodies 10 in the direction of arrow 14.

Each automobile body 10 is subjected to a spray of the

protective or decorative coating material emerging from or dis-

pensed by electrostatic spray devices 15 and 16 which are part

of the coating station. The electrostatic spray devices 15 and

16 are disposed on opposite sides of the conveyor line and each

are faced toward the conveyor line. The electrostatic devices and 16 are reciprocated in the vertical plane by suitable

reciprocators 17 and 18 so as to coat the sides of automobile

bodies 10. The -reciprocators 17 and 18 for the electrostatic

spray devices 15 and 16 may be carried by suitable movable bases

19 and 20. The movable bases 19 and 20 engage with guide tracks 21 and..92 so as to facilitate movement toward and away from the

conveyor line along the tracks 21 and 92 as the surface contours -I 9.9

18,234 of each automobile body 10 demand. The primary function of the

electrostatic spray devices 15 and 16 is to spray coating material

toward the side surfaces of each automobile body 10 as each auto-

mobile body passes thereby.

The spray painting station may also include an overhead

electrostatic spray device 22 faced toward the conveyor line.

Electrostatic spray device 22 may be vertically reciprocated 1 by any suitable reciprocator 90. As seen from FIGUREjX, the

spray device 22 is mounted so that it follows the surface contours

of the roof of the automobile body 10 thereby coating the roof

and the upper extremities of the front and the back of the auto-

mobile body with coating material. The electrostatic device 22

may include a plurality of electrostatic spray devices aligned in

a row across the top portion of the automobile body 10 in order

to properly coat such portions of the automobile body.

The middle and lower extremities of the front and the

back ends of each automobile body iO are coated by coating

material from the sprays of a plurality of back-to-back electro-

static spray devices 27 and 28 supported by an overhead member 29.

The overhead member 29 is operable to control the vertical position

of the back-to-back electrostatic spray devices 27 and 28 with

respect to the automobile bodies 10. The overhead member 29 may

include any suitable programmable device such as a hydraulic

device having a vertically displaceable piston 30. The vertical

position of the point 36 on piston 30 of the overhead member 29

determines the vertical position of the nozzles and the like of

the electrostatic spray devices 27 and 28 with respect to the

front and the rear surfaces of the automobile bodies In the particular enmbodiment illustrated in ie drawing,

,the electrostatic spray device ;U and 28, respectively, are 7 7.995

1 8 2 3 4 no carried and positioned by cross-bar members 31 and 32. The cross-bar members 31 and 32, carried by pivotally displaceable

arms 23 and 24, determine the distance between the nozzle and the like of each spray device 27 and 28 and the rear or front

ends or surfaces of the automobile body 10 and the position of tl

axis of the nozzle of each spray device with rqspect to rear or

front ends of the automobile bodies 10. The pivotal displacemeni of the arms 23 and 24 is controlled by hydraulic devices 33 and

34. Hydraulic devices 33 and 34 may include a cylinder and a

movable piston. The cylinder of each hydraulic device 33 and 34

is fixedly connected to the piston 30 of the overhead member 29.

Activation of either or both hydraulic devices 33 and 34 causes

their respective arms 23 and 24 to pivot about the point 36 on

the piston 30 to thereby appropriately space the nozzles and the

like from the front and the rear ends of the automobile bodies

and align each of the nozzles and the like of the flectrostati

spray devices with the surface of the irreqular contour to be

coated with coatina material.

It is seen that vertical displacement of the electro-

static spray devices 27 and 28, carried by the cross-bar members 31 3Z 340 and31, over the automobile bodies 10 is accomplished by dis-

placement of the point 36 of the piston 30 of the overhead

member 29. Further, it is seen that pivotal displacement of each electrostatic device 27 and 28 so as to space and aliqn the nozzlo and the like of the spray devices with the irregular contour of tl surface of the automobile body to be coated is accomplished by displacement of the cross-bar members 31 and 32 throuqh pivotal movement of the arms 23 and 24 by hydraulic devices 33 and 34. It is to be understood that each of the electrostatic devices 15, 16, 22. 27 and 28 is connected to a suitable direct- '8 427

18,2 34 M current source 35 capable of providing output voltages of up to

100 kilovolts or higher to each electrostatic device connected

thereto.

With continued reference to the several FIGURES of

the drawing and in particular to FIGURE 4, the movement of the

electrostatic devices 27 and 28 carried by cross-bar members

31 and 32, respectively, during a coating cycle will be des-

cribed. It should be understood that during a spray coating

cycle, the automobile bodies are substantially continuously

moving in the direction of arrow 14. Therefore, the relative

position of the automobile bodies 10 with respect to the verti- cal transverse plane of piston 30 is substantially continuously

changing during the coating cycle. Several positions of the

automobile bodies 10 with respect to the electrostatic devices

27 and 28 during a single coating cycle are illustrated by dotted

lines in FIGURE 4.

Upon activation of the hydraulic cylinder 30 by the

presence of automobile bodies 10, the hydraulic cylinder and,

hence, the-pivot point 36 carried by cylinder 30 is displaced

substantially continuously in a downward direction from its

initial position 40 until its lowest position at postion 45 is

attained. When the pivot point 36 attains position 45, the

direction of movement of the hydraulic cylinder 30 and hence

the direction of movement of pivot point 36 is reversed and

displaced substantially continuously in an upward direction to

its initial position, that is, position 40. In other words,

the hydraulic cylinder is moved into the gap or space between

adjacent automobile bodies 10 in the following operational

cycle: the initial position of pivot point 36 carried by

cylinder 30 is position 40; the pivot point 36 is displaced

18,234mn substantially continuously downward until position 45 is reach.

at which time the pivot point is.displaced substantially con-

tinuously upward until initial position 40 is reached, thereby

completing an operational cycle.

As the cylinder 30 goes through its vertical travel,

hydraulic cylinders 33 and 34 are programmed to pivotally dis-

place arms 23 and 24 respectively forward or rearward, as re-

quired, to appropriately move cross-bars membecs 31 and 32 to

thereby locate the electrostatic devices 27 a'nd 28 with respect

to the automobile bodies 10. When the electrostatic devices are

located, each is maintained at a substantially constant nozzle-

to-surface to be coated distance from the irregular surface

contours of the automobile bodies 10 being coated with coating

material.

The dotted line path provided by location points 49,

51, 52, 53, 54, 55, 56 and back to 50 and 49 illustrates the

location of the nozzle or nozzles and the like of electrostatic

device or devices 27 as substantially continuously moved verti-

cally and horizontally by the combined action of hydraulic

cylinders 30 and 34. As the nozzles of electrostatic devices 27

approach about location 52, it is contemplated that the electro- Z7 static devices 42 are activated or "triggered on" to thereby

emit coating material toward surface 82 at the front of the

trailing automobile body 10. At location 53, the electrostatic 27 devices&A' coat surface 83, and so on until the electrostatic

devicesA 8 return location 50 where the operational coating

cycle is completed by the coating of surface 87 at the front of

trailing automobile body 10. Thereafter, the.electrostatic 27 devicesj8 are de-activated or "triggered off". It should be

noted that as the trailing automobile body 10 moves toward the °]O S47995

182 3 4 no the electrostatic devices 28 vertical plane of cylinder 30, to maintain a more uniform nozzle- tend to be pivoted rearwardly distance. to-surface to be coated spacing or devices 28 The nozzles and the like of electrostatic dotted line path between loca- follow a path illustrated by the back to rocations tions 59, 60, 61, 62, 63, 64, 65, 66 and 28 are activated or "triggered and 59. The electrostatic devices the upper portion of surface 71' on" at about location 61 and coat body 10. At location 62 the at the'rear of leading automobile 72 at the rear of leading electrostatic devices 28 coat surface the electrostatic devices 28 automobile body 10 and so on until completing the coating of reach location 66 whereupon after automobile body 10, the elec- surface 76 at the rear of leading or "triggered off". It trostatic devices 28 are deactivated arm 24 tends to be pivoted for- should be observed that pivotal of the automobile body 10 as wardly in the direction of travel in the direction of arrow 14. the bodies move along the conveyor devices It should be understood that the electrostatic "off" during any portion of the 27 and 28 can be "triggered on" or 30 to obtain a uniform vertical movement of hydraulic cylinder surface. The sequence of triggering coating over the irregular27 the electrostatic devicesk and 28 recited above are merely and is not intended to illustrative of a typical coating cycle invention. limit the concepts involved in the present devices It should be understood that the electrostatic continuous manner 27 and 28 are being pivoted in a substantially maintain the approximate throughout the coating cycle so as to the nozzle and the like proper spacing and alignment between surface being coated with of each electrostatic device and the understood that the coating material. It should be further 11 199

18.23 4 /o electrostatic devices 27 and 28 may be retained at any particu

location without further pivotal displacement during any porti

of the cycle in order to obtain the desired coating thickness.

Where the automobile bodies 10 have a substantially vertical f

or rear surface or both, the arms 23 and 24 may be included wi

system of parallelogram like levers which avoid angling of t

devices 27 and 28 as the arms 23 and 24 are pivoted. With an automotive body design having more or less vertical surfaces at

the rear and at the front, angling .of the straying devices whil

arms 23 and 24 are pivoted is not desirable.

A further explanation of FIGURE 4 follows. The locat of pivot point 36 at position 40 finds the eL-.trostatic device

27 and 28 withdrawn from the gap or space between adjacent auto

mobile bodies 10 so that such devices 27 and 28 are not in an

interference path with the automobile bodies. Displacing the pivot point 36 from position 40 to position 41 causes the

electrostatic devices 27 and 28 to be displaced to locations 49

and 59 respectively. Displacement of the pivot point 36 from position 41 to position 42 displaces the electrostatic devices

27 and 28 to locations 50 and 60 respectively. During displace- ment of pivot point 36 from position 42 to position 43, the elec

trostatic devices 27 and 28 are pivotally displaced to locations

51 and to 61 respectively. During displacement of the pivot point 36 from position 43 to position 44, the electrostatic

devices 27 and 28 are pivotally displaced to locations 52 and 62

respectively. During displacement of the pivot point 36 from position 44 to position 45, the electrostatic devices 27 and 28

are displaced to locations 53 and 63 respectively. The pivot .point 36 remains at position 45 and the electrostatic devices 27 and 28 are displaced to locations 54 and 64 respectively. During 2t A97995.

2 3 4.no displacement of the pivot point 36 from position 45 to position 44, the electrostatic devices 27 and 28 are displaced to locations

and 65 respectively. During displacement of the pivot point

36 from position 44 to position 43, the electrostatic devices 27

and 28 are displaced to locations 56 and 66 respectively. During

displacement of the pivot point 36 from position 43 to position 42,

the electrostatic devices 27 and 28 are displaced to locations

and 60 respectively. The pivot point 36 is then displaced to

position 41 and electrostatic devices 27 and 28 are withdrawn

to locations 49 and 59 respectively. The pivot point 36 is then

displaced to position 40 thereby withdrawing the electrostatic

devices 27 and 28 from the gap or space between the automobile

bodies 10. While the nozzles of electrostatic devices 27 are at

positions 52, 53, 54, 55 and 56 the front end surfaces 82, 83,

84, 85 and 86 respectively of the trailing automobile body

are coated. While the nozzles of electrostatic devices 28 are

at positions 61, 62, 63, 64, 65 and 66 the rear end surfaces

71, 72, 73, 74, 75 and 76 respectively of the leading automobile

body 10 are coated.

A slight reciprocation of the electrostatic devices

27 and 28 in the horizontal plane across the surfaces of the

automobile bodies 10 may be desirable to facilitate blending

of the adjacent spray patterns emitted by the devices.

Programming of the overhead member 29 and hydraulic

devices 33 and 34 may be controlled by any suitable device (not

shown) such as a sequential camming-device which activates a

fluid valve or valves (not shown) to thereby regulate the fluid

flow into the cylinders associated with overhead member 29 and

hydraulic devices 33 and 34. The amount of fJ.iia flow into such

cylinders controls the movement or displacement of piston

ia IW7. 9

23.4/70 arms 23 and 24. and the movement or displacement of pivotal device It is contemplated that each electrostatic it at least one 16, 22, 27 and 28 will have associated with feeding paint to the air-atomizing nozzle, as well as means for delivered to the center of the nozzle; the paint so fed being atomized by the action nozzle of each electrostatic device and spray device is of air. A suitable air-atomizing electrostatic also understood illustrated in U.S. Patent 3,169,882. It is 27 anrd 28 may that each of the electrostatic spray devices device. For include more than one air-atomizing electrostatic spray example, it is contemplated that each of the electrostatic four air-atomizing devices 27 and 28 include at least a row of in U.S. Patent electrostatic spray devices of the type shown 3,169,882. other It is contemplated that electrostatic devices may be employed than air-atomizing electrostatic spray devices devices with the present invention. For example, electrostatic thereof and using a rotating head, hydraulic force combinations electrostatic the like may be substituted for the air-atomizing

devices 27 and 28.

The location of the various electrostatic spray devices line may 16 and 22 relative to each other along the conveyor

vary within relatively wide limits. It is desirable that each material of the electrostatic spray devices deposit the coating apart in overlapping patterns and should not be spaced so far by along the conveyor line that the coating material deposited

one electrostatic spray device will have dried before the over-

lapping spray is deposited.

The electrostatic spray coating devices may be auto-

matically activated upon the arrival of an automobile body 14 427995 l,23 4-no. at the paint spray station. A suitable automatic triggering or activation device may be used to sense the presence of the automobile body 10. The triggering device may be any suitable automobile body sensing means such as a feeler switch (not shown)' or it may include a light source 37 and a light-sensitive cell

38. The feeler switch or the light source 37 and the light-

sensitive cell 38 of the triggering device are so disposed that

the feeler of the switch is displaced from an initial or normal

position or the light falling upon the cell is interrupted when

an automobile body 10 is present in the coating zone, thereby

activating the spray coating devices through an appropriate

control apparatus (not shown). When an automobile body 10 has

passed from the coating zone, the feeler of the switch returns

to its normal or initial position or the light from light source

37 is permitted to impinge on light-sensitive cell 38 to thereby

reset the electrostatic spray apparatus through a suitable con-

trol device (not shown) for a subsequent coating cycle.

Although the member 29 including cylinder 30 is shown

as being installed overhead, it is recognized that the member 29

may be installed underground. In such an installation, the

apparatus is initially displaced upwardly and then displaced

downwardly to its initial position. Of course, the underground

apparatus must be so constructed as not to be in an interference

path with the automobile bodies as such bodies pass thereover.

.49,799"

Claims (3)

J. Z 4/70 The Claims defining the invention are as follows:-

1. A coating apparatus including means for

transporting spaced apart articles including front and rear surfaces having irregular contours to be coated through a coating zone, coating means including nozzle means for

dispensing particles of coating material toward the articles as the articles pass through the coating zone to deposit

particles of coating material upon the articles, programmed movable member means including arm means carrying the coating means and fixedly retaining the axis of tne nozzle means of the coating means at a right angle to the arm means, the movable member means including means for maintaining the nozzle means at a determined distance from the irregular surface contours of the articles by pivoting the arm means in the direction of movement of the articles about a pivot point removed from the coating means, and means for moving the coating means into the space between adjacent articles and simultaneously dispensing particles of coating material toward the front surface of one of the articlc3 and toward the rear surface of the adjacent article in the coating zone, the means moving the nozzle means of the coating means over each of the spaced apart articles in a plane transverse to the direction of movement of the articles as the articles are transported through the coating zone.

2. The coating apparatus of claim 1, wherein the coating means includes electrostatic coating means adapted to be connected to a high voltage direct current source.

18 427

18.234 /7n

3. The coating apparatus of claim 1, wherein the programmed member means aligns the axis of the nozzle means with respect to the planes of the irregular surface contours of each of the articles so as to be substantially perpendicular to such planes of each of the surface contours of the articles during at least a portion of the time the coating means is dispensing coating material toward the articles.

4. The coating apparatus of claim 3, wherein the articles having irregular surface contours are automobile bodies.

The coating apparatus of claim 4, wherein the coating means dispenses coating material toward the

irregular surface contours of a rear portion of the leading automobile body and of a front portion of the trailing automobile body.

6. Theff caim 1 further characterized by the step of aligning the coating means with respect to plane of the irregular surface.

Dated this llth day of July, 1972.

PANSBURG GmbH P- their Patent Attorneys, COLLISON CO.

8,2 3 4 no

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