US3703880A

US3703880A - Spray coating apparatus

Info

Publication number: US3703880A
Application number: US35030A
Authority: US
Inventors: David M Wampler
Original assignee: Libbey Owens Ford Co
Current assignee: Pilkington North America Inc
Priority date: 1970-05-06
Filing date: 1970-05-06
Publication date: 1972-11-28
Anticipated expiration: 1989-11-28
Also published as: GB1310452A; FR2088373B1; SE384454B; ZA712817B; JPS5231883B1; NL166630B; NL7106135A; DE2123017B2; DE2123017C3; IT944669B; DE2123017A1; LU63110A1; FR2088373A1; BE766689A; NL166630C; CA939140A

Abstract

Apparatus for spraying a uniform layer of parting material on the surface of glass windshield blanks prior to the bending thereof in laminated pairs. A composite spray arm oscillates vertically about a pivot point above a continuous conveyor upon which the blanks are advanced while horizontally disposed, and has a central telescoping section adapted to render the path of the lower end thereof substantially linear. A spray nozzle fixed to a member pivotally mounted on the lower end of the spray arm is adapted to pivot in conjunction with the oscillation of the arm so as to maintain the axis of the spray nozzle substantially vertical.

Description

[ NOV. 28, 1972 United States Patent Wampler FOREIGN PATENTS OR APPLICATIONS I54] SPRAY COATING APPARATUS ,441 4/1957 France.......................l18/323 589,479 3/1959 Italy...........................l18/323 T 1 d ,Oh'

o e O Primary Examiner-John P. McIntosh y 1970 Attorney-Collins and Oberlin [22] Filed:

[ ABSTRACT Apparatus for spraying a uniform layer of parting 21 Appl. No.: 35,030

[52] US. Cl. ......................l18/2, 118/323, 118/324,

material on the surface of glass windshield blanks prior to the bending thereof in laminated pairs. A composite spray arm oscillates verticall point abo blanks ar y about a pivot ve a continuous conveyor upon which the e advanced while horizontally disposed, and has a central telescoping section adapted to render the path of the lower end thereof substantially linear. A spray nozzle fixed to a member pivotall the lower end of the spray arm is adap 8 O0 7M7 HHH 9 9 353 202 14 2 m3 m3 2 u d .1 m M M C 2 mm m l. n m m m .m "h e R L d i to .mF 1 8 6 55 5 I UNITED STATES PATENTS y mounted on ted to pivot in conjunction with the oscillation of the arm so as to maintain the axis of the spray nozzle substantially vertical.

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A TTORNE YS SPRAY COATING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates broadly to the application of a uniform coating to a moving surface, and more particularly to an apparatus for spraying a liquid uniformly onto the surface of flat glass sheets.

2. Description of the Prior Art In the production of bent articles of laminated glass such as automobile Windshields, it is common practice to achieve the desired configuration by bending the constituent flat sheets (called blanks) in pairs to he contour of a mold. Bending is accomplished by placing each pair of blanks on a mold, and heating the sheets thereon to a soft, pliable state such that they bend by gravity to conform to the contour of the mold. In the softened physical state required for bending, however, associated pairs of untreated glass blanks which are to comprise a laminated windshield have an undesirable tendency to stick or even occasionally fuse together. It has therefore been customary to treat the blanks prior to bending by applying a film or coating of a parting material to that surface of each blank which subsequently becomes an inner surface of a laminar pair. The parting material is one which will both prevent any adhesion of adjacent surfaces and withstand the temperatures associated with the bending operation. One such material commonly used is a suspension of sodium sulfate.

The suspension of parting material is normally applied by a spraying apparatus repeatedly traversing across and above a conveyor on which the sheets are simultaneously advanced. The prior art practice has been to mount a nozzle spraying device rigidly at the lower end of a pivoting member which, in operation, swings back and forth in a substantially vertical plane making repeated arcuate passes across the conveyor. This apparatus has not proved entirely satisfactory, however, in that during the course of the arcuate path described by the nozzle, both the incident angle and the distance between the spray nozzle and the glass sheet change constantly. This results in application of a nonuniform layer of material across the width of the sheet. Thus, if, in the center where the nozzle is in close proximity with and spraying directly perpendicular to the glass sheet, an adequately thick layer is deposited thereon, then, at the edges where the nozzle is at a greater distance from and on an acute angle with the glass sheet, the resulting film is much to thin to protect the surface of the sheet. If the rate of spray be increased in order to assure the deposition of an adequate layer at the edges, an excess is applied in the center section, thereby producing a relatively heavy layer of parting material in that area which may cause discrepancies between the contours of the pair of sheets when subsequently shaped sufficient to produce visual distortion in the finished laminated product. Also, a substantial portion of the sprayed material itself is wasted.

SUMMARY The present invention contemplates an improved spraying apparatus which allows the application of a layer of substantially uniform thickness across the width of the glass sheet. An oscillating arm pivoted to swing in a substantially vertical plane telescopes to adjust the length thereof during each pass to maintain a substantially constant distance between the spraying means and the horizontal conveyor. In turn, a spraying nozzle is fixed to a member pivotally mounted at the lower end of the arm and provided with a connecting rod which pivots the member in conjunction with the swinging of the arm to keep the axis of the spray nozzle substantially vertical as it sweeps across the conveyor.

It is, therefore, a primary object of the present invention to prevent visual distortion caused by non-parallel surfaces in contoured laminated glass objects.

Another object of the present invention is to provide a swingably mounted spray apparatus which applies a layer of substantially uniform thickness to a surface perpendicular to its plane of oscillation.

Yet another object of the invention is to minimize the amount of material expended in applying a protective coating of parting material to glass sheets for preventing adhesion of the adjacent surfaces of mated pairs thereof in subsequent bending operations.

Still another object is to provide a swingably mounted oscillating spray apparatus which maintains a substantially constant distance and angle between the spraying means and the object being coated.

Other objects and advantages of the invention will become more apparent during the course of the following description when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 5 is an enlarged fragmentary front elevational view of the apparatus of FIG. 1 illustrating in broken lines various positions of the arm and spray nozzle.

DESCRIPTION OF THE PREFERRED EIVIBODIMENTS Referring now to the drawings, and in particular to FIGS. 1 and 2 thereof, there is shown generally at 10 a horizontal conveyor, nominally divided into three sections, namely an entry section 11, a spray section 12 and an exit section 13. A spray booth 14 enclosing the conveyor section 12 is shown partially cut away exposing a structural frame 15 supporting the spraying apparatus of the invention shown generally at 16.

The entry conveyor section 11 may be a conventional endless belt conveyor including a frame having spaced side rails 17 and end rails 18 supported on legs 19 resting on bases 20. Endless belts 21 span the length of the conveyor section, encompassing

end rolls

22 and 23, and are supported therebetween on slats 24 carried by the end rails 18. The

rolls

22 and 23 are carried on

shafts

25 and 26, respectively, suitably journaled in bearings at 27.

Of a similar construction the exit section 13 has a frame with spaced side and

end rails

28 and 29, respectively, supported by legs 30 resting on bases 31.

End rolls

32 and 33 are carried by

shafts

34 and 35, respectively, joumaled in bearings 36 and, with slats 37, are encircled by belts 38.

The center or spray section 12 has a frame structure including parallel, spaced side and

end rails

39 and 40, respectively, supported by legs 41 resting on bases 42. A series of spaced, driven joumaled shafts 43, span the side rails 39 and have a plurality of spaced, narrow collars 44, which may be made of rubber or similar resilient material, mounted in fixed positions thereon.

As best seen in FIGS. 2 and 3, flat glass blanks 45 are advanced in the general left-to-right direction as the conveyor system is driven by conventional drive means. Thus, a motor 46 through a drive system 47 (which may be a conventional chain drive) rotates the roll 22 and, through the resulting motion of the belts 21, drives the roll 23. The roll 23 in turn, is further connected to rotate a first drive shaft 48 in spray section 12, as by means of a chain drive at 49. A second drive shaft 50 in spray section 12 along with all of the spaced shafts 43 except the two end shafts of the series are driven in response to the rotation of the first drive shaft 48, through another conventional chain drive 51. The remaining shaft at each extreme of the series of spaced shafts 43 may then be driven in a similar manner from the adjacent intermediate shaft as by drive means 52 and 53. A final drive means 54 similar to those employed elsewhere in the system rotates the initial end roll 32 of the exit section 13 (and the end roll 33 through the resulting motion of the belts 38) in response to the rotation of the drive shaft 50. Thus, the individual segments of the conveyor system 10 may be made to operate in unison from a single motor.

In normal operation, the flat glass blanks 45 are placed on the entry section 11 and move continuously through the spray section 12 and along the exit section 13. Thus, it will be readily appreciated that the glass blanks are in continual horizontal motion throughout the spraying operation.

Turning now to the spraying apparatus itself, as best seen in FIGS. 1 and 3, the support structure includes legs 55 mounted on bases 55a and connected by conventional means with side horizontal members 56, top cross supports 57, lower cross supports 58 and

diagonal braces

59 and 60.

The spray arm of the invention, indicated generally at 61, swingably depends from the structure 15 supported by a stub shaft 62 joumaled in a pair of spaced bearings 63 supported, in turn, on a base 64 (FIGS. 3 and 5). The stub shaft extends through a sleeve 65 in the spray arm to which it is fixed as by keying at 66 (FIG. 4).

The spray arm itself is of a composite nature having segmented upper and

lower sections

67 and 68 with a central, tubular, telescoping section 69 therebetween. The upper section 67 has a lower segment 70, which may be tubular, slidably mounted in bushings 71 spaced within the section 69 (indicated by lines 71a). The lower section 68 includes an upper segment or element 72, which also may be tubular, threadably attached to the section 69 and a lower segment or element 73 to which a mounting plate 74 (FIG. 5) is swingably secured at 75.

A conventional drive mechanism is-mounted on the structure 15 and employed to oscillate the spray arm 61 on the stub shaft 62. The drive mechanism may include a motor 76 connected by means of a belt drive 77 with a gear reducer 78 of a reduction ratio compatible with the desired speed at the output shaft 79 thereof. The rotational motion of the output shaft 79 is converted into reciprocal motion, and this reciprocal motion is imparted to the spray arm 61, through a crank arm 80 and connecting rod 81 pivotally attached at the upper end 82 thereof. A plurality of attachment holes 83 located along the length of the crank arm 80 allows the length of the stroke of the spray arm 61 to be adjusted as required by simply changing the point of attachment ofthe rod 81 to the crank arm 80.

As mentioned above, the application by a conventional nozzle spray system of a coating of uniform thickness requires that the spray nozzle remain substantially equidistant from the target with its axis disposed at a substantially constant angle therewith during such application. To this end, the apparatus of the invention contemplates a spraying system which encompasses both of these requirements.

The distance-controlling portion of the invention which maintains a substantially constant vertical interval between a spray nozzle 84 fixed rigidly to the pivotal plate 74, and the blanks 45 passing .therebeneath, as best shown in FIGS. 3 and 5, includes a first horizontal shaft 85 rigidly fixed to the lower cross supports 58 of frame 15 and a second horizontal shaft 86 directly below the pivot shaft 62 secured to the telescoping member 69 of the spray arm 61. A connecting rod 87 linking the

shafts

85 and 86 is joumaled thereon as by sleeves 88. Thus, as the arm 61 oscillates across the conveyor 12, the rod 87 also oscillates, causing the member 69 to telescope in a manner which extends the arm as it moves from the center to the outer extremes of the swing and, conversely, retracts the arm as it approaches the center. This effects a leveling out of the arcuate path that would be described by an arm of constant length and maintains the nozzle 84 substantially equidistant from the plane of the .glass blanks 45 throughout the swing. The length of the rod 87 is such that the lineal, telescoping movement of the member 69 just compensates for the vertical displacement of the arcuate swing of a comparable rigid arm.

In addition to the above, a second pair of

rods

89 and 90 maintains the axis of the spray nozzle in a substantially vertical position throughout the swing of the arm 61. Thus, the rod 89 is rigidly fixed, as by a weld, to the connecting rod 87 so that the angle therebetween remains constant. The rod 90 is pivotally connected at 91 to the rod 89 and at 92 to the nozzle mounting plate 74. Thus, as the spray arm 61 oscillates, the

rods

89 and 90 cooperate to pivot the mounting plate 74 about the pivot point 75 relative to the lower spray arm segment 73, the plate 74 thereby maintaining a substantially horizontal line of travel and the axis of the nozzle 84 remaining substantially vertically disposed.

The spraying mechanism of the spray nozzle 84 is operated in response to signals from limit switches 93 and 94 (FIG. 3) by compressed air from lines 95 and 96 as will be hereinafter described. The limit switches 93 and 94 are attached to the framework of the conveyor section 12 so as to be depressed by the glass blanks 45 as they travel thereover. Thus, the limit switch 93 is located a short distance ahead of the nozzle 84 and the limit switch 94 a short distance past the nozzle 84, in reference to the general left-to-right travel of the glass blanks 45. When the leading edge of a blank depresses the initial limit switch 93, compressed air is supplied to the line 95 to open internal valving (not shown) in the nozzle 84, thereby simultaneously releasing air from the line 96 and spray medium supplied from a source through the line 97. The nozzle sprays continuously until the trailing edge of the blank 45 releases the second limit switch 94. This system assures complete spray coverage in the direction of travel of'the conveyor as spraying begins just before the leading edge of the blank reaches the nozzle and ceases just after the trailing edge thereof passes beyond the reach of the spray.

Thus, by means of the present invention an essentially uniform spray pattern is maintained at the level of the blanks 45, thereby coating their entire surface with a uniform layer of parting material. Also, consumption of the sprayed solution is reduced significantly as it is no longer necessary to compensate for possible underspraying at the side edges.

To review briefly the operation of the system, with all three

conveyor sections

11, 12 and 13 continuously operating and spray arm 61 continuously oscillating, glass blanks 45 are loaded on section 11 and advanced therealong. As the leading edge of a blank 45 depresses the initial limit switch 93, spraying is actuated and continues until the trailing edge releases the second limit switch 94, shutting off the spray nozzle. The spray arm 61 is normally oscillatedat a relatively fast rate in comparison with the rate of advancement of the glass blanks 45 and thus, in effect, the blank receives a series of overlapping finely sprayed layers to produce the desired total layer thickness of the sprayed material. The coated blanks then pass on along the exit section 13 ready to be paired up for the bending operation to follow. If the blanks 45 are placed close together on the conveyor system such that the limit switch 93 is depressed by a subsequent blank before the limit switch 94 is released, the spray nozzle, of course, will operate continuously.

Although the invention has been described with reference to the application of a particular material, i.e., parting material for laminated windshield blanks, it is contemplated that any similar sprayable material may also be applied to a flat surface by the invention.

1 claim:

1. In apparatus for depositing a coating material on the surface of horizontally disposed glass sheets advancing along a predetermined path, the improvement comprising an extensible arm pivotally mounted above said path for movement in a plane transversely of said path, said extensible arm including at least two sections axially movable relative to each other for adjusting the length of said arm, means carried by said arm at the lower end thereof for depositing said coating material on said sheets as they pass therebeneath, means swinging said arm back and forth about said pivotal mounting whereby said means for depositing said coating material swings with said arm and repeatedly traverses across said advancing sheets, and means adjusting the length of said extensible arm in response to said back and forth movement whereby said means carried by said arm for depositing said coating material maintains a substantially uniform distance from said sheets as it moves thereacross, said means adjusting the length of said arm comprising a connecting rod having a stationary end independently attached to the support structure below the picot point of said arm and a traveling end attached to said extensible arm.

2. Apparatus for depositing a coating on the surface of horizontally disposed glass sheets as claimed in claim 1, wherein said material depositing means comprises a spray nozzle fixed to a mounting member attached to the lower end of said arm and adapted to pivot in a vertical plane, and including a connecting rod attached to said mounting member and adapted to pivot said mounting member in conjunction with said swing to maintain an essentially constant angle of incidence between the axis of said nozzle and said sheets as said nozzle traverses said conveyor.

3. Apparatus for depositing a coating on the surface of horizontally disposed glass sheets as claimed in claim 2, wherein said connecting rod and mounting member maintain the axis of said nozzle in a substantially vertiv cal position as said arm traverses across said sheets.

4. Apparatus for depositing a coating on the surface of horizontally disposed glass sheets as claimed in claim 2, wherein said predetermined path comprises a conveyor and including means actuating and shutting off the spraying mechanism of said nozzle in response to movement of glass sheets on said conveying means into and out of position for spraying.

5. Apparatus for depositing a coating on the surface of horizontally disposed glass sheets as claimed in claim 1, wherein said means swinging said arm includes a drive means supplying rotational motion, a crank arm attached thereto, and a connecting rod pivotally attached to said crank arm and spray arm transforming said rotational motion into reciprocal motion pivotally oscillating said spray arm.

6. Apparatus for depositing a coating material on the surface of horizontally disposed glass sheets as claimed in claim 1; wherein said extensible arm is pivotally mounted on a pivot shaft and comprises segmented upper and lower sections and a central tubular section therebetween, said upper segmented section including an upper member having means adapted to mount said arm on said pivot shaft, said upper member being attached to said swinging means above said pivot shaft, and a lower member fixed thereto and telescopically mounted within said central tubular section for axial extension and retraction of said arm, said lower segmented section including an upper element affixed to the lower end of said central tubular section and a lower element fixed to said upper element and adapted to carry said means for depositing said coating material at the lower end thereof.

7. Apparatus for depositing a coating material on the surface of horizontally disposed glass sheets as claimed in claim 1, wherein said means swinging said arm includes a drive means supplying rotational motion, a crank arm attached thereto, and a connecting rod pivotally attached to said crank arm and spray arm transforming said rotational motion into reciprocal motion pivotally oscillating said spray arm, and said material depositing means includes a spray nozzle fixed to a mounting member attached to the lower end of said arm and adapted to pivot in a vertical plane and a connecting rod attached to said mounting member and adapted to pivot said mounting member in conjunction with said swing to maintain an essentially constant angle of incidence between the axis of said nozzle and said sheets as said nozzle traverses said conveyor.

Claims

3. Apparatus for depositing a coating on the surface of horizontally disposed glass sheets as claimed in claim 2, wherein said connecting rod and mounting member maintain the axis of said nozzle in a substantially vertical position as said arm traverses across said sheets.