US3619311A

US3619311A - Method of programming a controller

Info

Publication number: US3619311A
Application number: US52018A
Authority: US
Inventors: Glenn R Rose; Robert S Hedin
Original assignee: PROGRAMMED AND REMOTE SYST CORP
Current assignee: CIMCORP GCA CORPORATION'S; Programmed and Remote Systems Corp; PROGRAMMED AND REMOTE SYST CORP
Priority date: 1970-07-02
Filing date: 1970-07-02
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

A method of programming a controller for an oscillating spray painter to paint an object that moves past the sprayer. A scale drawing of the object is superimposed on a developed layout of the path of the sprayer. A control member for the controller is divided into sections corresponding to the strokes of the sprayer and the points where painting should begin and stop during each stroke of the sprayer are determined from the scale drawing and then correspondingly placed on the control member.

Description

United States Patent Inventors Appl. No.

Filed Patented Assignee Glenn R. Rose St. Paul;

Robert S. Hedin, Minneapolis, both of Minn.

July 2, 1970 Division of Ser. No. 838,020, June 19, 1969, Pat. No. 3,561,398, which is a continuation of Ser. No. 561,882, June 20, 1966, abandoned Nov. 9, 1971 Programmed 8: RemoteSystems Corporation St. Paul, Minn.

METHOD OF PROGRAMMING A CONTROLLER 4 Claims, 16 Drawing Figs.

ll7 /l05.3, ll7/DlG. 2,118/305, 118/323 511 1111.01 B31b1/62 so FieldofSearch 156/62; 118/305. 323; 1 17/1053, 105.4, DIG. 2

[56] References Cited UNITED STATES PATENTS 2,852,305 9/1958 Shaffer 118/305 X 2,966,881 1/1961 Enssle 118/323 X Primary Examiner-Benjamin A. Borchelt Assistant Examinerl-larold Tudor Arwrney- Dugger, Peterson, Johnson and Westman ABSTRACT: A method of programming a controller for an oscillating spray painter to paint an object that moves past the sprayer. A scale drawing of the object is superimposed on a developed layout of the path of the sprayer. A control member for the controller is divided into sections corresponding to the strokes of the sprayer and the points where painting should begin and stop during each stroke of the sprayer are determined from the scale drawing and then correspondingly placed on the control member.

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PATENTEnunv 9 I971 3.6 1 9 3 1 1 sum 9 [IF 9 FIG 14 irrazvz s METHOD OF PROGRAMMING A CONTROLLER CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of our copending application Ser. No. 838,020, filed June 19, I969 for SPRAY PAINTER, now Pat. No. 3,561,389, which in turn is a continuation of our application Ser. No. 561,882, filed June 20, 1966 for SPRAY PAINTER, now abandoned.

SUMMARY OF THE INVENTION The present invention has relation to a spray painting mechanism and more particularly to a programming and operative system which moves a spray gun in a first direction as an item to be sprayed is moved past the gun in a transverse direction.

The spray nozzle positioning system of the present invention has an ann mounting a spray gun which is reciprocated up and down about an arm axis. The spray am is linked to a motor driven cam to provide essentially constant velocity of the nozzle over the painted area. Also, linkages are provided to maintain a reference plane of the nozzle spray fan oriented in space despite accurate movementof the spray arm.

Additional mechanism is provided to cause the arm to move in and out in a contoured path to follow approximately the contour of an auto body. The spray painter is designed primarily for use in connection with auto bodies and the contour feature aids greatly in obtaining unifonn painting on the body.

A programming drum is utilized which controls the on and off positions of the spray gun. By the use of a plurality of photocells and corresponding preprogrammed control tapes, several different auto body types can be painted interchangeably. The device is programmed so that the paint spray will shut off in the portion of the arm travel where there is no surface to be painted. For example, over the hood and trunk areas of sedans, wheel cutouts, and in the window areas.

The device is made so that each painting cycle consists of 18 complete arm cycles or 36 painting strokes. This corresponds to one revolution of the programming drum. If all the strokes are not used for an auto body, for example, a compact car, the arm completes its full number of strokes to reset the system, but the nozzle would be shut off whenever there was no surface to be painted.

The control system is also designed to permit manual operation or automatic operation, as desired.

It is an object of this invention to present a spray painter which can be programmed for the spraying and painting operation.

It is further object of the present invention to present a spray painter that can be used with automobiles traveling on a conveyor and wherein at least one axis of the spray is maintained parallel to a reference plane at all times during its stroke or cycle.

It is further object of the present invention to present a spray painter for use with automobiles or the like wherein the painting gun can be moved in and out in a contour approximating the contour of a side surface of an automobile.

It is another object of the present invention to present a spray painter wherein the painter can be programmed to stop the paint spray in preselected points of its travel.

Other objects are inherent in the specification and will become apparent as the description proceeds. In the drawings,

FIG.. 1 is an end elevational view of a spray painter made according to the present invention;

FIG. 2 is a top plan view of the painter of FIG. 1;

FIG. 3 is a side elevational view thereof with parts in section and parts broken away;

FIG. 4 is a view taken from the side opposite from FIG. 3;

FIG. 5 is a sectional view taken as on line 55 of FIG. 3;

FIG. 6 is a fragmentary perspective exploded view of a control mechanism used to give proper spray gun orientation when contour surfaces are being painted;

FIGS. 7 and 8 are side views of the device of FIG. 6 shown in two different positions;

FIG. 9 is an enlarged fragmentary sectional view of a gear box shaft and drive crank for the spray gun control;

FIG. 10 is a fragmentary enlarged plan view of the spray gun support with parts in section and parts broken away;

FIG. 11 is a sectional view taken as on line 1l1l in FIG. 10;

FIGS. 12A and 12B are schematic representations of the controls for the spray unit;

FIG. 13 is a schematic illustration of a typical painting sequence obtained with the device of the present invention;

FIG. 14 is a part schematic view of a master slave painter;

FIG. 15 is an end view showing a modified contour control.

Referring to the drawings and the numerals of reference thereon, a spray painter assembly illustrated generally at 10 is positioned adjacent a conveyor line (shown only schematically in FIG. 12B) of conventional design on which automobiles 11 or similar objects to be painted are mounted. The automobiles move past the sprayer assembly, and when they are properly positioned with respect to the painter, a photoelectic cell is operated to actuate the sprayer. Cycle start" and cycle stop switches are well known in the art and can be microswitches or other devices as well as photoelectric devices. The spray painter comprises a spraying head assembly 12 of usual air operated design in which solenoid valves control operation which is mounted onto an arm assembly 13 that pivots about a substantially horizontal axis 14 (see FIG. 1) and which will thus basically move up and down in an arc as indicated by arrows 15. The arm assembly is operated about its axis in a manner that will be explained later. Thus, as the automobile moves past on the conveyor in direction as indicated by the arrows 16 in FIG. 2 and the spray gun move up and down, the spray painting actually forms continuous W configuration on the auto body (see FIG. 13) The spray pattern, the speed of movement of the spray gun, and the speed of movement of the conveyor itself are correlated so that the item is completely painted as it passes.

The paint sprayer assembly comprises an outer cabinet 20 in which is mounted a main frame assembly 21. The frame 21 is used for mounting all of the components that drive the spray gun. The frame 21 is used to mount a drive motor 22 which in turn drives through a variable output speed reducer 23 and gear box 24 to rotate a main operating cam 25. The cam 25 is mounted onto an output shaft of the gear box 24 and as shown has an irregular outer periphery. The cam rotates in the direction as indicated by arrow 26. A cam follower assembly 27 is mounted so as to engage the cam and includes an arm 30 which is mounted on a shaft 31 that in turn is rotatably mounted in a pair of bearings 32 which are attached to an upright member on the mainframe 21. The arm 30 has a pin 33 at its outer and and a roller 34 is rotatably mounted on the pin and rides against the outer surface of the cam. The cam roller oscillates as it follows the cam surface.

Also mounted at the outer end of arm 30 is a small bracket 35 to which a push link 36 is pivotally mounted. The link 36 is attached to the bracket 31 with suitable rod end spherical bearings conventionally known. The outer end of link 36 is pivotally attached as at 37 to a lever arm 38 which in turn has a hub that is drivably mounted onto an output shaft 40 of gear box 41 which is mounted to the frame 21. The shaft 40 of the gear box is mounted on bearings inside the gear box and it extends through the gear box and out through a wall of the cabinet 20. The painting arm assembly 13 has a hub 42 which is drivably mounted onto the outwardly extending end of shaft 40 outside of the spray painter cabinet 20. The hub 42, as shown, is square in cross section and is bored to receive the shaft. The arm assembly 13 includes two actuating

arms

43, 43 pivotally mounted as at 44, 44 about upright axes to the hub 42. The

arms

43, 43 are spaced apart and are parallel. The arms are attached to the hub 42 with yokes 45, 45 that are bifurcated to fit over the hub The yokes are fixed to the ends of the arms. The outer ends of the

arms

43, 43 are pivotally mounted about

axes

46, 46 to the spray head assembly. The

axes

46, 46 are parallel to the axes 44, 44 so that the two

arms

43, 43 always remain parallel.

The spray gun assembly 12 will be explained more fully later in the specification. The pivotal mountings are merely shoulder bolts 73 fastened to the spray gun assembly and passing through provided housings on the

arms

43, 43.

As mentioned previously, the

arms

43, 43 move as a unit in up and down direction about the axis 14 of shaft 40. The arms are also controlled so that if desired they can be made to move in and out in an are as they move up and down. The contour control linkage is illustrated generally at 50, in FIG. 2.

As shown, there is a support arm 51 to which a contour bar 52 is pivotally mounted as at 53. The movement of the contour bar about its pivot 53 is controlled through the use of an air cylinder 54 attached to the frame adjacent the support arm 51 and having a rod attached as at 55 to the contour bar. The contour bar is made so it will slide in direction as indicated by arrow 56 along a support 57 from position against a first stop 58 to a second stop 59. The support 57 is made of two spaced apart bars as shown and the contour arm slides between the bars. The stops 58 and 59 are merely bolts extending through provided slots in the bars making up the support 57 which are tightened onto spacers in the desired position. The contour bar 52 has a leg 62 at the end opposite from pivot 53. The leg 62 is positioned so that it will extend around the end to the side of the housing for the paint sprayer device. The leg 62 in turn has an upright support member 63 fixedly attached thereto.

One end of a small universal joint 64 is attached to the upper end of upright arm 63 and the order end of the universal joint 64 is attached to a lug 65 which extends from a swinging arm 66. The swinging arm 66 is made up of two sections and is longitudinally adjustable in its length as shown. The opposite end of the swinging arm 66 has a lug 67 on which one end of a universal joint 68 is attached. The opposite end of the universal joint 68 is attached to a link 69 which in turn is fixedly attached to the yoke 45 on the outboard arm 43. The link 69 extends outwardly in opposite directions from the arms and thus will move up and down in an arc when the arms move up and down.

The contour movement (or in and out movement) of the spray head, controlled by the

arms

43, 43 which will permit the movement of the spray gun to follow the contour of a car as shown in FIG. 1 is controlled by the swinging arm 66. When the arm 66 is in its first stopped position again stop 58, the pivotal axis of universal joint 64 is aligned with the pivotal axis of shaft 40 and the hub 42. When the

arms

43, 43 are driven up and down as shown by arrow 15, the arms will not move in and out at all because of the alignment of these axes. The swinging arm 66 and its attached link 69 move as a unit about the same axis as the hub 42. There will be no in and out

movement ofarms

43, 43.

However, when the contour bar 52 is moved against the stop 59, the axis of the swinging am 66 no longer aligns with the axis of shaft 40. When the

arms

43, 43 move up and down the link 69 also moves up and down and the end of arm 66 attached to the link must follow. Because the swinging arm 66 is attached to the universal joint 64, the end of the arm 66 at link 69 is forced to move in an are about the pivot of U" joint 64. The arcuate movement of arm 66 means that the effective length of arm 66 changes in transverse direction. This forces the link 69 to move transversely in and out and thereby move the

arms

43, 43 in and out. It, of course, should be noted that the

arms

43, 43 remain parallel and the main spray head body axis remains in its initial orientation in transverse direction.

It is desirable to have the spray gun always remain perpendicular to the contour or body surface. Thus where the body is contoured, the angle of the spray axis of the spray gun should change slightly in its vertical plane of movement to remain perpendicular to the surface. This angular change is shown in dotted lines at 72 in FIG. 1. In order to accomplish this, a compensating linkage has been developed. First, in order to understand the linkage, the mounting of the spray gun itself should be explained.

As shown in FIGS. 10 and 11, the spray gun assembly 12 is pivotally mounted about the

axes

46, 46 at the outer ends of

arms

43, 43. The arms are attached through pins 73 which pass through hubs 74 in the ends of arms 43 and have shoulders thereon so that the arms can pivot on the pins. The pins pass through a main mounting block 75 for the spray head assembly. The outer edge mounting block 75 is bifurcated or relieved and has a first leg 76 and a second leg 77 which are spaced apart. The main frame 75 is used for mounting a gun holder assembly 78. The gun holder assembly has a gun mounting member 79 which comprises an arm having a pin 80 at one end for holding the spray head and having a two piece bifurcated hub 81 which has opposite ends mounted onto aligning

coaxial pins

82 and 83. The

pins

82 and 83 are attached to a block 84 which in turn is mounted onto a pin 85. The pin 85 is positioned at right angles to the axes of

pins

82 and 83. The pin 85 passes through and is rotatably mounted with respect to a tubular housing or sleeve 86 which in turn is rotatably mounted in the second leg 77 of frame 75. The pin also passes through a provided bushing 87 in leg 76 of the frame 75. A bushing is also used inside the housing 86 for mounting pin 85.

A control arm 88 is drivably attached to the other end of the pin 85 and extends upwardly therefrom. The angular position of the spray head about the axis of the pin 85 is controlled through the use of the arm 88 which is attached to a link 89 as at 90. Suitable rod end members are used on the link 89. The opposite end of the link 89 is pivotally attached with respect to the main frame as at 94 (see FIGS. 1 and 5) on a suitable housing or support. The pivot axis of the link 89 and 94 is substantially vertically about the axis of the shaft 40. Thus the link 89 acts as a parallel link to maintain the same angular position of the spray mounting member 79 with respect to a horizontal plane as the

arms

43, 43 oscillate up and down. In other words the pin 85 will rotate slightly with respect to its mountings when the

arms

43, 43 oscillate up and down, but will thereby keep the orientation of the spray pattern with respect to a vertical or horizontal plane identical throughout the travel of the arms. Even though the spray gun describes an are as it moves at the outer ends of

arms

43, 43 the spray pattern will remain oriented so that its vertical axis initially will remain its vertical axis of the spray pattern throughout the travel. This is important because many times the spray pattern is not circular, but has a longer dimension for example in vertical direction than it does in transverse direction and so the orientation of the spray pattern is important.

Also, a second upper parallel link 96 is positioned to control movement of the spray gun during contour movement of the

arms

43, 43. During normal oscillation of the spray arms, without any contour adjustment, the link 96 and link 89 move in exactly the same pattern, and about the same axis of pivot.

The link 96 is pivotally attached at its rear end (see F 10$. 1, 2 and 3) as at 97 to a control arm 98 which in turn is attached to a shaft 99. The shaft 99 is rotatably mounted in suitable bearings 100 above the gear box 41. The movement of the shaft 99 is controlled in a manner which will be explained subsequently. The pivots for the

links

89 and 96 are spherical pivots so the links can pivot up and down and in and out as well.

The link 96 is attached at its outer end adjacent the spray gun head as at 101 to a second control arm 102 which in turn is clamped on to the housing 86. The arm 102 controls rotation movement of the housing, with respect to the mounting member 75.

The housing 86 has a gear segment 103 attached thereto for rotation therewith, which is actually a portion or sector of a ring gear and this gear segment 103 meshes with a second gear segment 104 which is integral with the holder member 79 for the spray gun.

The

gear segments

103 and 104 control the angular position of the holder member 79 about the

pins

82 and 83, and thus control the movement of the spray gun or head in a vertical plane about

pins

82 and 83. As stated previously, it is desirable to have the axis of the spray from the spray gun perpendicular to the surface being painted. Thus if the surface is vertical, the axis of the spray gun noule should be in a horizontal plane. However, where there is a contour surface to be painted, the surface deviates from vertical and therefore the axis of the spray gun must deviate from horizontal. The

arms

43, 43 will move in and out when properly set to accommodate the contour. When the contour is zero, or in other words when the

arms

43, 43 do not move transversely during their cycle, then the spray gun also remains oriented in space and the two

links

89 and 96 act as parallel links. The angular position of the spray gun remains the same in space. There is no relative motion between the

gears

103 and 104. The

links

89 and 96 both operate about the same axes and control movement of the gun about the axis of pin 85 so that the axes of

pins

82 and 83 remain horizontal. Compensation to hold the spray oriented is accomplished by moving the link 96 while holding the link 89 in its normal position to cause the spray gun to tip up or down about pins 82 and 83. The movement of the link 96 is controlled by the shaft 99 and its arm 9 8. In order to rotate the shaft 99 a control yoke 107 is drivably mounted as at 108 to the end of the shaft 99 opposite from arm 98. The yoke extends downwardly and has a long slot 109 defined therein (see FIG. 6) A slider 110 is positioned within the slot 109 and is free to slide up and down with respect thereto. The slider is mounted rotatably onto a pin 11] which is press fitted into a second slider 112 that is slidably mounted in a slot 113 of a control yoke 114. in addition, the other end of pin 111 is rotatably mounted in a third slider 115 that is mounted in an open sided slot 116 defined in a crank 117 that is mounted onto the outer end of shaft 40. As explained previously, the shaft 40 oscillates back and forth, and when it does this, it will move the crank arm 117. Depending upon the positions of the

sliders

115, 112 and 110 with respect to the axis of the shaft 40, the crank arm thus determines the motion of the yoke 107.

The position of the pin 111 with respect to the axis of shaft 40 is controlled by the yoke 114. The yoke 114 is mounted onto a pair of

parallel arms

120 and 121 which are pivotally mounted to the yoke as at 122 and 123, respectively, and are pivotally mounted onto the frame as at 124 and 125, respec tively. A spring 126 is attached between the yoke and the frame to urge the yoke in downward direction. The movement of the yoke is in turn controlled by a bell crank 127 that is pivotally mounted as at 128 to the main frame, and has a pin 129 that engages the pin used at pivot 123 for the lower link 12] on the yoke. The pin 129 engages the underside of the pin at pivot 123 and the position of the bell crank determines how far downwardly the yoke 114 can travel. When the pins are in engagement and the bell crank is held, the yoke cannot travel downwardly any further.

The position of the bell crank about its pivot 128 is controlled by a rod 112 which is slidably mounted through the sidewall of the frame and is attached as at 133 to an outwardly extending portion of the contour bar 52. The attachment 133 is positioned on an opposite side of the pivot 53 from the main part of the contour bar. A spring 134 is mounted over the link 132 and urges the link outwardly to return the bell crank to its down position. The link 132 is attached as at 135 to the bell crank 127.

When the contour bar 52 is in its no contour position as shown in FIG. 2, the link 132 permits the bell crank to move downwardly and this in turn allows the yoke 114 to move downwardly to position wherein the pin 111, carried by the slider 112, is axially aligned with the axis of rod or shaft 40. (Note that the

links

120 and 121 are arranged so that slot 113 remains horizontal). In this position, called the no contour" position, the yoke 107 is not moved and

links

89 and 96 act as parallel arms. Both move about common axes at pivot 94. The two

gear sectors

103 and 104 remain stationary with respect to each other. The

links

89 and 96 merely compensate for the arcuate movement so that the axis of the spray gun remains at its normal orientation as the

arms

43, 43 and the spray gun oscillate up and down.

When the contour bar 52 is moved to its contour" position as shown in dotted lines at 140 against the stop 59, so that the

arms

43, 43 are pivoted by the swing am 66 about their axes 44, 44 and move in and out in a contour pattern, the link 132 is moved inwardly in direction as indicated by the arrow 141. The pin 129 will then act against the pin at pivot 123 and will push the yoke 1 l4 upwardly. This will move the slider 112 up wardly and, of course, move the pin 111 upwardly. The slider 115 will move in the slot 116, slider 112 will move the slot 113, and slider will move in the slot 109 the necessary amount to permit the pin 111 to move away from the axis of the shaft 40 as the yoke 114 moves upwardly.

What this will do is to move the axis of pin 111 and shaft 40 out of alignment to make the crank 117 effective to cause an oscillatory motion of the pin 111. Because the yoke 114 is held stationary, this motion of the crank 117 will cause the pin to move back and forth in the slot 113 rather than in an arc. The slider of course will slide in slot 116 to permit this.

Movement of the pin 111 and slider 110 back and forth will cause the yoke 107 to move back and forth about the axis of shaft 99 as indicated by double arrow 142. This in turn will oscillate the shaft 99 and move arm 98 and link 96 back and forth. The arm 102 will rotate, thereby rotating the housing 86 with respect to the shafi 85 which is held by link 89. Gear 103 on housing 86 will drive gear 104 and thereby rotate the holding member for the spray gun about the

pins

82 and 83. This will cause the axis of the spray gun to change with respect to the horizontal. By proper selection of the lever arm ratios, including the lengths of the yoke 107, arm 98, and the spacing of the bell crank pivot on bell crank 127, the gun tip up can be adjusted to insure that the axis of the spray coming from the gun will be perpendicular to the surface that is being painted. This compensatory efiect is necessary only when the contour adjustment is working.

The paint is supplied to the spray gun through usual or preferred devices, and the flow of paint is controlled automatically by solenoid operated control valves. The control of the solenoid operated valves in turn is responsive to a photoelectric control system. in the form as shown, photocells are mounted adjacent a drum 151 which drivably mounted on a shaft 152 that is rotatably mounted on suitable bearings 153 on the main frame. The drum is driven through a chain and sprocket drive 154 to a jack shaft 155 that in turn has a large sprocket 156 which is driven by a chain 157 operating from a sprocket 158 drivably mounted on the shaft for the cam 25. Suitable chain tighteners can be provided for the chains.

Whenever motor 22 is driven, it will drive the arms with cam 25 and also rotate the drum. The drum is used for automatic operation and the photocells are of a type that respond to reflected light. The cells have a light source that shines toward the drum and also contain in one housing a light sensitive photoelectric cell.

Strips

160, 298 of reflective tape are placed on the drum and one is aligned with each photocell. Where the sprayer is to paint, the reflective surface is left. This energizes the aligned photocell to initiate spraying. When there is to be no spraying the tape is painted a light absorbing black. Therefore light will not reflect and the photocell will not operate.

Several photocells and control tapes can be mounted. Each tape would be programmed for a different spraying sequence. However, only one photocell and control tape would be active at one time. This will be better understood after the control circuitry has been explained, referring to FIGS. 22A and 128.

To operate the device, which will operate either in manual or automatic position, a main disconnect switch is closed and power is supplied to the line contacts for the motor and also to a power select switch 171. The power to the power select switch can be a lower voltage than that used for the motor if desired, and in normal cases the motor will operate on 240 volts while the power select switch will receive only 1 15 volts. The power select switch 117 gives a choice of either manual or automatic operation, designated MAN and AUTO, respectively.

7 MANUAL OPERATION When switch 171 is placed in Man" position, parallel relays 172 and 1173 are energized through line 169. Line 169 extends from switch 171 to a common return line 168. The relay coils 172 and 173, which operate in parallel, apply power to the manual bus or line 175 through the closing of normally open contacts 172A. Also, normally closed contacts 173A in a line 166 are opened and normally open contacts 1738 in line 166A are closed. Normally closed contacts 173C in line 167 are opened and normally open contacts 173D in line 167A are closed. This disconnects a cam drive motor relay 180 in line 166 and a contour solenoid coil 181 which is in line 167, from the automatic operation bus or line.

Also coil 172 causes normally closed contacts 1728 to open and nonnally open contacts 172C to close, thereby illuminating the indicator lamp 184 to show that power is on.

Then, upon depressing the manual spray pushbutton 187 in a line 188, a relay 189 is energized. This will open normally closed contacts 189A in line 166 and close normally open contacts 18913 in line 166B, which in turn is connected between line 166A and line 166. The relay 189 also closes normally open contacts 189C in a line 193 which connects to a main line 194 leading through a closed manual cut out switch 195 to a spray gun control solenoid coil 196.

The relay 180 will be energized through lines 166A, 1668 and a closed manual cut out switch 197. This will close

contacts

180A and 180B in the motor circuit to energize the cam drive motor 22. This will initiate the oscillation of the

paint spraying arms

43, 43 through the previously explained mechanism.

At the same time, with switch 195 closed, solenoid 196 is energized and this will in turn operate a suitable valve or valves illustrated schematically at 202 to in turn actuate the spray gun 203 of the assembly 12, to initiate the spraying operation. Then, under this manual operation, the arm will move up and down as previously described and the paint will be sprayed onto a car or other object traveling past on the conveyor, as long as the button 187 switch depressed. The spray gun can be stopped by opening switch 195. Thus, manually, without affecting the drive to the arms, certain areas can be left unpainted.

If a contour is desired, a manual contour select switch 204 in line 167A is moved to its position shown in dotted lines. This then will energize solenoid 181 through contacts 173D (which are now closed) which in turn will actuate valve 205 which in turn will direct air under pressure to the cylinder 54. This will move the contour bar 52 to its outward stop position against the stop 59 and cause the spray arms to move in the predesired contour as previously described. When deenergized, the solenoid coil 181 relaxes and permits the air cylinder 54 to move so that the contour bar is in its no-contour" position. The spraying continues as long as switch 187 is closed. When opened, the motor 22 stops and the spray gun 203 quits spraying paint.

Before attempting automatic operation, the control drum 151 must be in its start position. This is indicated as follows. When the selector switch 171 is placed in manual position and relay 173 is energized, in addition to the contacts already mentioned, the relay will open normally closed contacts 173E and will close normally open contacts 173F. The contacts 173E are in a line 208 in which a normally closed microswitch 209 is placed. The microswitch 209 is operated from a cam 210 shown schematically in FIG. 12A and driven by the shaft 152 for the programming drum of the unit. When the drum is in its home position the cam 210 will open the normally closed Contacts of switch 209 and connect line 208 to a line 211 in which an auto ready" indicator light 212 is wired. When the light 212 is lit, it is known that the programming drum is at its start or home position.

If it is not properly set, the programming drum can be reset to its starting position by pushing a switch 215 which will connect a line 216 to the manual bus bar or line 175 thereby energizing a relay 217. Relay 217 closes normally open contacts 217A in line 208 and also closes normally open contacts 2178 in line 166 leading to the coil 180.

The push button 187 will not be depressed because there will be no manual spraying at that time, so normally closed contacts 189A will be closed. The relay 180 will be energized through line 166A, contacts 173C which will be closed, contacts 2178 which will be closed, and normally closed contacts 189A, closed switch 197 and then through the overload contacts provided, as shown at 220. Energizing the relay 180 again will start motor 22 to drive the drum to its home position. The drive will be locked on through the contacts 217A, switch 209 and contacts 173F until the cam 210 opens the microswitch 209 and closes its nonnally open contact illuminating the indicator light 212. Once the switch 209 opens in line 208, then relay 217 is no longer energized (contacts 217A will then open) and the motor relay 180 will also be relaxed because contacts 2178 will open.

A dynamic brake is utilized in motor 22 and is automatically energized to bring the system to a quick stop.

The unit can be operated by pushing the manual pushbutton 187 in order to, as previously described, operate the spray gun and drive motor 22 for the spray arms. If the switch 204 is properly set, the contour solenoid coil 181 will be energized to in turn actuate the cylinder 54 for moving the contour bar.

AUTOMATlC OPERATION The unit is designed primarily to run automatically. The device is synchronized and interlocked with a conveyor on which the autos to be painted are mounted. Referring specifically to FIG. 12B and the schematic representation in the upper part of the HQ, a conveyor 222 of known design is used for moving an automobile 223 past the spray painting mechanism. A conveyor drive motor 224 is used for driving the conveyor 222 and is powered through a source of power 225. An electrical interlock is utilized between the drive for the conveyor 222 and the controls for the paint sprayer. This interlock is actuated through the use of a relay 226 in the conveyor motor circuit which controls contacts 226A that are normally open, normally closed contacts 226B, normally open contacts 226C and normally open contacts 226D. These contacts are in

lines

230, 231, 232 and 234, respectively. The coil is related to these contacts with the dashed line in the schematic drawing.

Thus, when automatic operation is to be effected with the main power switch 171 on, the power selection switch is turned to the AUTO" position and this energizes an automatic bus bar or line 235. It also cuts off the line or bus bar 175 for manual operation because the

relays

172 and 173 are deenergized opening contacts 172A and also permitting the contacts 173A-F and 1728 and 172C to go to their normal positions. As soon as the line 235 is energized, the power on" indicator lamp 184 will be illuminated through normally closed contacts 172B. In addition, a main control photoelectric unit 236 is energized. The photoelectic unit is a unit made up of a usual design according to well-known principles and has a relay 237 internally which operates contacts 237A and closes these contacts when it is energized. The relay 237 is connected through suitable circuitry so that it is energized in response to light actuating one of the photoelectric cells 150.

The painting program for each automobile body is on one annular row or ring 60 of tape having intermittent reflective surfaces. The photocells are highly discriminative and will only respond to the reflections from the tape in the annular row with which they are aligned so that the complete painting program for one automobile body is in an annular row around the drum and the painting is effected when the photocell is aligned with one of the reflective sections.

While several different auto bodies can be programmed interchangeably on the programming device, the present disclosure illustrates only two such programs. It is to be understood that others can be added if desired merely to providing the necessary relays, interlocks and pushbuttons for selecting the type of car body to be painted.

For example, with a sedan 223 on the conveyor, selection is made by pushing the proper type select button, either 240 or 241 (FIG. 12A) just below relay 236. Assuming that the type selection button 240 is the one for this type of automobile, the button is pushed completing a circuit through line 242. This in turn energizes

relays

243 and 244 and lights a type indicator" light 245. Coil 243 closes normally open contacts 243A and 2433 which then activates a light source or lamp 247 and a photoelectric cell 249 through unit 236. Further relay 244 closes normally open contacts 244A and opens normally closed contacts 2448. The opening of contacts 244B opens the circuit to the other type select system shown, and the closing of contacts 244A locks the

relays

243 and 244 in energized position through line 254. In addition, if the type of body, for example the sedan shown, controlled by pushbutton 240 has a contour surface that has to be painted, a manual contour select pushbutton switch 255 is closed (near bottom of FIG. 12A). A second contour select switch 256 goes in conjunction with type switch 241 and operates in the same manner, but will remain open. Relay 244 also closes a set of normally open contacts 244C to connect line 167 through switch 255 to the bus bar 235 and thus solenoid coil 181 is energized through contacts 1738 which are normally closed. The air valve 205 is actuated and cylinder 54 moves the contour bar 52 to its proper position.

Referring to FIG. 12B it can be seen that the energizing of bus bar or line 235 also energizes a paint start photoelectric unit 260. The paint start photoelectric unit has a relay 261 which, when energized will close normally open contacts 261A which are connected through a line on one side thereof to the bus bar or line 235. The photoelectric unit 260 is controlled from a light source 263 that is illuminated whenever the unit 260 is energized and the energization of coil 261 is designed to occur when light from the light source 263 no longer reaches a photoelectric cell 264. The light source 263 and cell 264 are positioned on opposite sides of the conveyor 222 so that when an automobile is positioned between the light source and the photocell, relay 261 will become energized closing contacts 261A. In addition, relay 243, which was energized at the time pushbutton 240 was depressed, and remains energized through closed contacts 244A (locked on), will close a set of contacts 243C positioned in a line 266 leading from contacts 261A.

Energization of relay 226, when the conveyor 222 starts closes contacts 226C as previously explained, then connects an adjustable time delay relay 269 to power. The relay 269 is made so that its coil will not operate until a predetermined time after energization. During this time the conveyor motor 224 will run and will be permitted to take up slack in the conveyor which normally occurs. The relay 269 will be timed so that it will energize after the slack has been taken out and as soon as the car 223 starts to move. When the relay 269 operates it will close contacts 269A thereby completing a circuit through contacts 226A (which will be closed when relay 226 is energized), and a connecting line 271 to a relay 272. When relay 272 is energized, it closes contacts 272A and also closes normally open contacts 2728 in line 194 leading from the photorelay unit 236 (FIG. 12A) to the relay 196 that operates the spray gun. This will make the operation of the spray gun dependent only upon the closing of contacts 237A in response to energization of relay 237 in the photorelay 236. The relay 272 also closes contacts 272C in line 166 (FIG. 12A). The relay 272 locks on through its contacts 272A, line 271 and normally closed contacts 275A which bypass contacts 226A. Then, once the auto 223 intercepts the light coming from light source 263 to photoelectric cell 264, relay 261 will be energized and contacts 261A will close. This will transmit power from line 235 through contacts 261A, line 266, contacts 243C (which were closed by relay 243 FIG. 12A) to the line 276 and thus to energize the relay 277. Relay 277 controls the start of the paint spray gun. It closes a pair of contacts 277A in line 276 to lock on through normally closed contacts 279A which are connected to line 235. Coil 277 also closes normally open contacts 2778 which energizes a coil 284 to engage a clutch in an automatic adjustable timer 285. Referring back to FIG. 12A, the relay 277 also closes normally open contacts 277C which connect line 235 through normally closed contacts 287A to line 216 thereby energizing relay 217. This coil 217 closes contacts 217A and 2178 (as previously described) completing a circuit through line 166, contacts 272C, which were closed by coil 272, normally closed contacts 173A, contacts 217B, normally closed contacts 189A and closed switch 197 to energize the motor control relay and thereby start motor 22 to rotate the drum. As the drum 151 rotates, portions of a strip 160 of reflective tape will pass over the photoelectric cells 150 and light from lamp 247 will be reflected by the reflective portions of the tape to energize the photoelectric cell 249 thereby energizing relay 237 and closing contacts 237A. This will transmit power from line 235 through line 194, switch and closed contacts 2728 to start the spray gun 203 by energizing the coil 196 which controls the valve to the spray gun.

It should also be noted that the energization of coil 217 closes contacts 217C (FIG. 12B) which lead to a timer motor 279 in timer 285. The timer is set for a fixed period of time which corresponds to the length of time to travel between car bodies. Once started, the unit will be locked on and not responsive to photocell 264. This will help prevent false starts between bodies. The timer deactivates the unit shortly before a new body aligns with light 263 and cell 264.

During the time that the drum is rotating, the dispensing of paint through the spray gun is controlled only by the photoelectric cell 249 and lamp 247 on their counter parts which in turn are controlled by the reflective sections of tape on the drum. The paint cycle will shut on and off in a sequence that can be predetermined by programming the tape on the drum.

When relay 277 (FIG. 12B) is energized, it also closes normally opened contacts 277D in a line 294 and this supplies power to a slow operated time delay relay 287. Once this relay 287 energizes, after contacts 277D close and thus after the drum has been rotated for a short time (relay 277 is not energized until the drum is driven), the relay 287 opens normally closed contacts 287A (FIG. 12A) thereby disabling the direct connection from line 235 to line 216 and relay 217. However, the delay before relay 287 is energized is sufficient to permit the cam 210 on the shaft for the drum 151 to move to position to permit the switch 209 to move to its normally closed position thus completing a circuit through normally closed contacts 206, switch 209, contacts 217A and thus to line 216 and relay 217. The relay 217 is then looked on until the cam 210 rotates sufficiently far to open switch 209. This will only occur after the complete cycle of the drum has been made. When the switch 209 again opens, the drum will be stopped because relay 217 will relax opening contacts 2178 in the circuit for motor 22.

Relay 277 remains locked on until the time period set on timer 285 elapses. At which time the timer opens contact 279A thus breaking the circuit to relay 277 and releasing all its contacts. The releasing of coil 277 and contacts 277B resets the timer clutch internally and also releases relay 287 (contacts 287A closed) in preparation for the next automatic start which will be triggered by an auto coming between light source 263 and photoelectric cell 264.

If the conveyor interlock system for motor 224 indicates a conveyor stoppage, the coil 226 is deenergized releasing

contacts

226A, 226B, 226C and 226D. This will pennit contacts 2263 to close energizing a relay 275 in line 231 which controls contacts 275A that are used to lock on relay 272. Relay 275 is a slow operating adjustable relay which will permit the sprayer to operate while the conveyor coasts to a stop. The contacts 275A remain closed to keep the painting circuits operating until enough time has clasped so that the conveyor does stop. After the predetermined length of time has elasped, contacts 275A will be opened breaking the circuit to relay 272 and thereby opening contacts 272A and 272C, immediately stopping the motor 22 for the drum and paint sprayer and also disabling the solenoid operating the spray gun. The time lapse before relay 275 is energized after relay 226 relaxes can be adjusted to permit this coasting stop of the conveyor.

If the automobile on the conveyor is of a different type having a different tape program on the drum, button 241 would be depressed in place of button 240 and this would energize

relay

301 and 302 which would operate contacts 301A and 3MB disabling the previous circuit connected through button 240 and energizing a light 305 to indicate that this is the circuit operating. In addition, if the type of automobile body being painted has a contour, the switch 256 would be closed and relay coil 302 would operate contacts 302A to complete the circuit previously made through contacts 244C to actuate the coil for the air cylinder 54 operating the contour bar. Relay 302 would also close normally open contacts 302B (H6. 123) which would connect line 266 to line 276 in the same manner that contacts 265 made this connection. In addition, contacts 301C and 301D would be closed by coil 30] energizing light source 313 and photoelectric cell 314 which would now control coil 237 and contacts 237A in place of the photoelectric cell and light source 247 and 249, respectively.

The rest of the operation would take place exactly the same way, because contacts 3028 would just take the place of contacts 243C and the on and off control for the paint spray gun itself would be actuated by the photorelay 236 but would be controlled by the difi'erent programming of the tape 298 which reflects the light from source 313 and thus operates photoelectric cell 314. Thus the programming could be different from this different type of body.

In FIG. 13, the pattern made on the auto body as it passes the paint gun is shown. Also, in conjunction therewith is shown a tape strip 160 to give the desired operation. The spray gun makes a W" configuration as shown. Its home position is at the bottom of line 1. The tape home position is also at the bottom. When the cam 25 starts, drum 151 also starts rotating. The spray gun is not turned on until the gun reaches the bottom of the auto body 1A. At 1A the tape reflective portion 1 will cause painting. Painting will stop at 13 when a dark portion of the tape passes in front of the photocells. This corresponds to IE on the auto body. Thus the tape is programmed to start and stop painting at desired points. The program can be placed on the tape prior to the time the tape is put on the drum.

The layout of FIG. 13 shows the start and stop positions on each of the strokes of the painter, 2A, 28, 3A, 38, etc. The painter is programmed for 36 strokes or l8 complete cycles. The tape is then divided into 36 portions, shown as l, 2, 3, etc. by actual measurement from the reference line to the shut off and turn on marks on the cycle. These marks can be placed on the tape. Of course the different scales can be compensated for very easily.

It should be noted that because of a time lag between the shutting down of the solenoid controlling the spray gun and the actual stopping of the dispensing of paint, and conversely a time lag between the time the solenoid is energized and the time paint actually starts to be dispensed, the actual operation or actuation of the photocell will either lead or lag the position of the spray gun. The shutoff and turn on marks are depicted by the small cross marks at 2A and 2B for example. The marks indicate the points at which photocell is either energized or deenergized and it can be seen at these points that they do not correspond exactly with the peripheral edges of the car. This adjustment is made to make sure that the painting occurs at the right instant even though there may be delays in the system.

The tape can easily be preprogrammed. This is essentially a drafting procedure. The path of the spray gun in relation to an item on the conveyor is reproduced as shown in FIG. 13 to exact scale. The path representation, of course, is dependent upon the conveyor speed which must be preselected. The pattern would be different at different conveyor speeds. With a spray for width of 1 foot, the conveyor speed in feet per minute must equal the arm speed in cycles per minute. This is shown in FIG. 13. A scale model of the template of the auto body to be painted is superimposed over or under the scale layout depicting of the nozzle travel.

The template is positioned so that it is in proper relation to the position of the start" photocells 263-264. Marks are then made on each stroke to indicate the turn on and shut off points. The turn on and shut off points are compensated for contour, time lag and other factors afi'ecting the particular system. The distance between the actual stroke marks will represent the portion of the stroke during which the gun will be turned on. The corresponding information can be transferred to the tape, starting at the home position. The scale can be chosen to fit the particular situation. Inasmuch as the peripheral distance of the drum is known, and the painting sprayer is set so that 36 strokes make a complete painting cycle, it is known that each stroke will represent 10 on the periphery of the drum. Thus, by knowing the portion of each stroke during which painting is to occur, the tape can be accurately marked at the turn on and shut off points for each stroke. Adjustments for contour painting and system lags can be made merely by changing the on and off points to suit. This also can be graphically done. Then the portions where there is to be no paint dispensed will be blackened with a light absorbing or flat black lacquer or paint. The information can be obtained by measuring the distance to each turn on and shut off point on each stroke from reference lines L and L, and the measuring of a corresponding amount on the tape, and marking it. The reference lines represent the end and beginning of each stroke.

Once the tape has been completely marked as desired to accommodate the different auto bodies being painted, it will then be transferred onto the drum aligned with one of the photocells. The use of a pressure sensitive tape permits removal of the tape for marking the program onto the tape when it is lying flat. This simplifies the task of marking the program. Also the tapes can be easily changed, if desired, for easy removal, only the ends of the tape need to be fixed to the drum.

It should be noted that the photocells each comprise a unitary light source with a photosensitive cell. The light sources are concentric with the photosensitive cell and will project a light beam up against the tape. in the reflective portions the light will be reflected back to the photosensitive cell causing energization of that particular unit. For example, one of the photocells 150 would be represented on the schematic drawing 12A by light source 247 and photocell 249.

While the specific example shown has been in regard to painting of automobiles with the gun traveling in an up and down direction, it should also be noted that the same principle of utilizing parallel linkage to maintain the orientation of the spray throughout the arm travel can be used to great advantage in painting flat surfaces which are horizontal. In this instance, the horizontal surface member would be carried past the sprayer, and the sprayer would move transversely above or below it. Holding the spray gun oriented permits an even application of paint across the entire surface of the device being painted.

As the cam 25 rotates, the roller 34 rides along its surface. This actuates the push link 36 and oscillates am 38 and shaft 40. The shaft is returned down by gravity.

It should also be noted that spherical seats on the rod ends

links

89 and 96 permit the links to swivel in and out for contour operation, as well as pivot up and down.

The contour linkage, 50 in FIG. 2 and in particular swinging arm 66, can be adjusted in length to accommodate cars of different widths. Shortening the arm 66 (the arm has two sections held by bolts in slotted holes) has the effect of moving the spray head inward toward the car. Because of the differences in lever arms about the pivots 44, a small adjustment of the arm 66 causes a relatively larger movement of the spray head. As shown on the drawings, the adjustment of the contour links is done manually by means of the bolts and elongated slots shown. The adjustment for various car widths could also be done automatically by including an air cylinder in the arm 66. With the air cylinder extended, the spray head would be in position for wide cars, and with it retracted, the spray head would be in position for narrow cars. The air cylinder would be controlled at the time the car type" is selected, in a manner similar to which the contour-select" air cylinder is controlled. The pushbutton and solenoid controls would be added to the electrical circuit in the same manner.

in the operation of the paint sprayer of the present invention, it is desirable to paint two sides of an automobile at one time. As shown in FIG. 14, in part schematic form, two paint sprayer assemblies are positioned on opposite sides of the conveyor line and are simultaneously operated to enable painting both sides of an automobile at once. The unit described in detail in this specification is considered to be the master unit and the unit indicated at 320 is a slave unit that duplicates the motions of the master. Only one set of controls is utilized, however, and when necessary, for example the spray gun control, the controls are merely hooked in parallel so that both spray guns are operated at the same time from the same signal.

in order to operate the master and slave arms mechanically in their oscillation, and in synchronization, the gear box 41 as shown in FIG. 5, has a downwardly depending shaft 321 which is driven through bevel gears from the shaft 40 inside the box 41. The driving of shaft 40 has previously been explained. The shaft 321 on the master is coupled to an elongated shaft 322 that extends downwardly through the cabinet for the sprayer and through provided openings in the floor below the sprayer cabinet and extends into a first gear box 323. The first gear box 323 is mounted in any suitable manner below the floor and is a right angle drive gear box. An output shaft 324 extends transversely underneath the floor and across the width of the conveyor 222 and automobile 223 thereon. Shaft 324 drives a second gear box 325 that is also positioned beneath the floor directly below the slave sprayer unit 320. An output shaft 326 extends upwardly from this right angle gear box 325 and is coupled to the shaft 321 of the gear box 41 in the slave unit 320. Thus the shaft 321 in the unit 320 becomes the drive shaft and will, upon rotation, drive the shaft 40 in gear box 41 of the slave unit. This will cause the arms to oscillate at the same time that the arms of the master unit are operating. Likewise, the same parallel linkage is utilized with the arms of the unit 320 and gun tip up is controlled in the same way from the main shaft 40 of this unit. Synchronization is accomplished by setting both sets of anns at their home positions and connecting the drives.

Only one programming drum is necessary because the controls all run from the master unit and thus the slave merely duplicates the movement of the master unit and is made to paint the opposite side of the automobile from the master.

It is to be noted that the contour linkage can be operated on the slave in the same manner and merely by having parallel controls for the air cylinder.

in FIG. 15 a slightly modified attachment for the contour bar is shown to give a different type of contour at the top of the stroke than at the bottom. As previously explained, by moving contour bar 52 out from alignment of the axis of the shaft 40, there will be an equal amount of contour above and below the center of the stroke of the arms. However, by lowering the pivot axis of the swinging arm 66, at the same time the contour bar 52 is moved outwardly, the amount of contour can be changed so that there is less contour at the top and more contour at the bottom of the automobile illustrated at 330. This is done by making the arm 63 adjustable. As shown in FIG. 15, this arm is now numbered 331 and has two

sections

332 and 333 that are joined together by bolt means 334 extending through provided upright slots in the two arm sections. Lowering the pivot of universal joint 64 will skew the contour of the spray arms about their pivots, as shown. This aids in matching the contour of automobiles presently being made. Thus by lowering the pivot of the swinging arm below the pivot axis of the oscillating paint arm 43, a greater amount of contour can be made at the lower end of the arm arc. By raising this pivot axis, a greater amount of contour can be made at the upper or top part of the stroke of the arms 43.

it should also be noted that this adjustment can be made with an air cylinder in place of the two sections 331 and 332 of the upright am. An air cylinder control could be added just as the controls for the contour bar is presently accomplished. Merely by pushing a button, the skewing of the contour can be made by either raising the effective pivot of the swinging arm 66 above the pivotal axis of the painting arms.

What is claimed is:

1. A method of programming a controller which shuts off and turns on a dispensing unit which dispenses material on an object passing by the unit as the unit oscillates in direction transverse to the direction of movement of the object, said controller comprising control means controlling dispensing through a complete, known cycle of the dispensing unit, including the steps of:

making a scale drawing of the developed path of the oscillating unit during an operative cycle,

superimposing a drawing of the object on which the material is to be dispensed at the same scale as the drawing of the developed path,

marking on the drawing of the developed path the points where the dispensing should start and stop,

dividing the control means into sections corresponding to each of the strokes of the unit during its cycle,

placing start and stop indicia on the control means in each of the sections in position corresponding to the position of the marks on the scale drawing.

2. The method of claim 1 and the further step of adjusting the stop and start marks on each section to compensate for operative lags in the dispensing mechanism.

3. The method of claim 1 wherein the control means includes a drum, a light reflective tape on the drum, a photocell means responsive to the reflective portions of said reflective tape to control dispensing, and including the further step of darkening the areas on the tape with a nonreflective material where no material is to be dispensed.

4. The method of claim 3 including the step of laying the tape on a flat surface for marking the stop and start points, then placing the tape around the periphery of the drum in proper position and adhesively fastening it in place.

a x r a a UNETED STATES PATENT (n nes QERTELFFLQATE SF CGRRECTWN Patent 3,6l9j3ll Dated November 9, 1971 Inventor(s) Glenn R. ROSE! et 6.1

It is certified that error appears in the above-identified patent and that said Letters Patent are ilsii'ialllj corrected as shown below:

g. Golumn 1, line 6 "3,561,389" should be--3.,56l,398-;

Column 1, line after "is" insert--a--; Column 1, line after "is' insert--a--. Column 2, line 33 move" should be --moves--; Column 2, line 51 'am? (first occurence) should be --end-- Column 2, line 72 after hub insert--period Column 5 line 53 "112" should be--l32--. Column 7, line 39 "switch" should be-is--. Column 8, line 63 "6@" should be --l-- Column 8, line 73 "to" should be-by--.

Signed and sealed this 25th day of A i 1972.

(SEAL) Attest:

EDWARD M. FLETCHER, Ji-i Attesting Officer H0553? GUTTSCHALK Commission or of Patents

Claims

2. The method of claim 1 and the further step of adjusting the stop and start marks on each section to compensate for operative lags in the dispensing mechanism.
3. The method of claim 1 wherein the control means includes a drum, a light reflective tape on the drum, a photocell means responsive to the reflective portions of said reflective tape to control dispensing, and including the further step of darkening the areas on the tape with a nonreflective material where no material is to be dispensed.
4. The method of claim 3 including the step of laying the tape on a flat surface for marking the stop and start points, then placing the tape around the periphery of the drum in proper position and adhesively fastening it in place.