Spray applicator for roofing and other surfaces

A method and an industrial robotic device for uniformly applying coatings at appropriate thickness and pitch upon a surface moves a spray applicator foam dispenser between two parallel tracks. The uniform application of foam at each pass is assured, by accelerating the speed of the foam dispenser at the end of each pass, by providing respective curved uphill distal ends of the tracks, so that the spray applicator foam dispenser moves up the curved distal ends and returns quickly while changing speed tilt and direction at the end of each pass.

FIELD OF THE INVENTION 
The present invention relates to a new and useful method and industrial 
robotic device for applying coatings or other spray coated layers, in 
uniform thicknesses and at appropriate angles of pitch, in field 
applications, such as roofing applications or pavement applications. 
BACKGROUND OF THE INVENTION 
In the roofing applications, flat roofs are often made of polyurethane foam 
layers, which may be covered by various coatings, such as elastomeric 
coatings, such as silicone. It is difficult to maintain a uniform 
thickness when applying a foam or elastomeric material, which by its 
nature rises when applied to achieve a thickness above a roof base. 
Furthermore, the faster that a foam applicator passes over a surface, the 
less volume of foam is applied, resulting in less of a thickness of the 
applied foam. To achieve thicker foam layers, a spray applicator is slowed 
down in velocity as it passes over the roof bases, so that more foam 
material is discharged per square unit of space of roof base being passed 
over by the spray applicator. 
Various attempts have been made to apply foam uniformly, such as from an 
applicator moving at a uniform speed along a carriage track. However, at 
the end of each pass of an applicator over a portion of a roof base, the 
discharged foam is applied twice, i.e. once at the end of the pass to the 
edge, and again as it starts over above the previously applied foam, until 
the carriage can adjust to an unsprayed area. 
Among prior art devices include U.S. Pat. No. 5,381,597 of Petrove which 
describes a wheeled robotic device for installing shingles on roofs. While 
it does not concern spraying of urethane foam upon a flat roof, it does 
describe a movable, wheeled carriage for use upon a roof. 
U.S. Pat. No. 5,248,341 of Berry concerns the use of curved walls to 
accommodate spray paint applicators for curved surfaces, such as aircraft. 
U.S. Pat. No. 5,141,363 of Stephens describes a mobile train which rides on 
parallel tracks for spraying the inside of a tunnel. 
U.S. Pat. No. 5,098,024 of MacIntyre discloses a spray and effector which 
uses pivoting members to move an armature which holds a spray apparatus. 
U.S. Pat. No. 4,983,426 of Jordan discloses a method for the application of 
an aqueous coating upon a flat roof by applying a tiecoat to a mastic 
coat. 
U.S. Pat. No. 4,838,492 of Berry discloses a spray gun reciprocating 
device, wherein parallel tracks are used wherein each track is square in 
cross section, but further wherein each track guides a plurality of 
rollers thereon. 
U.S. Pat. No. 4,630,567 of Bambousek discloses a spray system for 
automobile bodies, including a paint booth, a paint robot apparatus 
movable therein, and a rail mechanism for supporting the apparatus 
thereat. 
U.S. Pat. No. 4,567,230 of Meyer describes a chemical composition for the 
application of a foam upon a flat roof. 
U.S. Pat. No. 4,167,151 of Muraoka discloses a spray applicator wherein a 
discharge nozzle is moved transversally upon a frame placed adjacent and 
parallel to the surface having the foam being applied thereto. However, 
the applicator of Muraoka '151 does not solve the problem of excess foam 
being applied at the end of each transverse pass of the discharge nozzle. 
U.S. Pat. No. 4,209,557 of Edwards describes a movable carriage for a 
nozzle applying adhesive to the back of a movably advancing sheet of 
carpeting. Similarly, Australian Patent no. 294,996 of Keith describes a 
movable carriage for a nozzle applying a polyurethane foam coating to a 
movably advancing sheet. 
U.S. Pat. No. 4,016,323 of Volovsek also discloses the application of foam 
to a flat roof. 
U.S. Pat. No. 3,786,965 and Canadian Patent no. 981,082, both of James et 
al, describe a self-contained trailer for environmentally containing a 
dispenser for uniformly dispensing urethane foam upon a terrestrial 
surface, wherein the problem of "skewing" occurs at the completion of each 
pass at the boundary edges of the surface to which are urethane foam is 
being applied. James '965 employs self-enclosed gantry robots to move the 
fluid discharge nozzle over the terrestrial surface. 
U.S. Pat. No. 3,667,687 of Rivking discloses a foam applicator device. 
U.S. Pat. No. 4,474,135 of Bellafiore discloses an apparatus for spraying a 
coating upon a spherical object supported by a post, which apparatus 
includes a curved track for providing orbital movement of a spray 
applicator about the exterior spherical surface of the sphere to be 
coated. While they are curved in nature, the curved tracks thereof are 
provided for orbital movement about the sphere, not to change the speed, 
tilt and direction of a linearly moving nozzle. 
Another attempt to solve the problem of "double spraying" at a pass edge 
has been described in U.S. Pat. No. 4,333,973 of Bellafiore, which 
describes a similar spray applicator, such as that of Autofoam.RTM. 
Company. This spray applicator includes a wheeled, self-movable vehicle 
having a carriage portion with a horizontal linear track thereon. The 
spray applicator moves from one end of the track to the other, opposite 
end of the track at the end of one pass, of the applicator, above a 
portion of a roof base, and then the applicator reverses direction upon 
the track. 
However, to avoid the "double spraying" problem noted above, the 
Autofoam.RTM. device has an on-off switch which turns the applicator off 
at an appropriate time at the end of a pass while the applicator is 
reversing direction, and re-starts the applicator a short time later when 
the applicator has started to move in the opposite direction. 
Moreover, there are severe problems with this approach, as the constant 
"on-off" starting and re-starting of the applicator causes fatigue to the 
metal or other material parts of the applicator, and a detrimental effect 
to the end product. In addition, the Bellafiore '973 and Autofoam.RTM. 
devices are bulky and complicated to use. 
OBJECTS OF THE INVENTION 
Therefore, the objects of the present invention are as follows: 
It is therefore an object of the present invention to provide a spray 
applicator for foam roofing which applies a coating of elastomeric foam of 
uniform thickness. 
It is also an object of the present invention to provide a single yet 
efficient spray applicator for foam roofing. 
It is also an object of the present invention to provide a spray applicator 
that can be disassembled into a few major parts for easy transport and 
reassembly on a roof without resorting to the use of a crane. 
It is yet another object of this invention to provide a method for covering 
a large area of a roof with foam roofing using a continuous spray. 
It is also an object of the present invention to provide a spray applicator 
with a nutating nozzle mount to minimize variations in coating thickness. 
It is a further object of the present invention to provide a hand-held 
remote control to enable the spray applicator vehicle to operate without 
an on-board operator. 
It is an object of the present invention to provide a method for continuous 
adhesive spraying and application of elastomeric sheet roofing material of 
large strip areas of a roof. 
It is a further object of the present invention to provide accessories for 
the spray applicator vehicle to permit its use for applying elastomeric 
sheet roofing material from a roll. 
Yet another objective of this invention is to provide a method and 
apparatus to provide fabric reinforced foam roofing. 
It is also an object of the present invention to improve over the 
disadvantages of the prior art. 
SUMMARY OF THE INVENTION 
In keeping with these objects and others which may become apparent, and to 
solve the problems inherent in the Bellafiore '973 and Autofoam.RTM. 
spraying devices, the present invention uses one or more track rails, such 
as a double linear track of round cross section, as shown in the drawings 
herein, wherein there is an arcuate uphill end portion of the track at 
each side, so that the spray applicator, which moves along the one or more 
linear tracks, will accelerate in speed and tilt the discharge nozzle 
outward as it rolls up the curved uphill portion, thereby reducing the 
amount of foam applied to the edge portion of the roof at the end of a 
pass of the applicator. 
To obviate the complicated mechanisms of the Autofoam.RTM. device, the 
present invention uses simple mechanics to move the spray applicator. For 
example, a radially extending swinging arm is provided for the sideways 
movement of the applicator along the track. To eliminate arcuate movement 
of the pivoting arm, a telescoping mechanism is provided, so that the 
spray applicator moves linearly, instead of arcuately, as the swinging arm 
moves about a pivot fulcrum point. 
To further insure uniform thickness, the present invention further 
comprises various speed controls, so that an appropriate thickness can be 
applied for each pass. 
For example, a rheostat controls the speed of the movement of the spray 
applicator, and an LED readout tachometer has a display dial with 
appropriate readings for appropriate speeds for corresponding desired 
thicknesses. Since the rate of flow of foam-producing material emanating 
from the nozzle is fixed, the ground movement speed of the applicator 
determines the weight of the coating per unit area applied. This, in turn, 
determines the thickness. 
When a slope is desired on a flat roof, such as toward a drainage line, the 
ground speed of the foam applicator can be reduced on each successive pass 
away and parallel to the drainage line. This will result in a stepwise 
slope approximating the desired contour. 
It has been found that a nutating nozzle holder, which tilts the nozzle a 
small amount cyclically as it traverses the track, can be used to minimize 
the variations in foam thickness (in the form of rounded ridges) due to 
the hollow-cone pattern of the nozzle. 
Accessories can be added to the spray applicator so that it can be adapted 
for spraying adhesive on a roof or for automatically laying an elastomeric 
sheet covering such as Sure-Seal.TM. Fleece Back 100 EPDM made by Carlisle 
SynTec Incorporated of Carlisle, Pa. over a polyurethane foam substrate. 
Accessories can also be added for imbedding reinforced fabric within the 
polyurethane foal substrate. 
While the invention has been described for use in applying roofing 
materials on roofs, it is also usable for spray applications at ground 
level such as for pavement painting or sealing applications.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIGS. 1-2, spray applicator 1 is used for applying polyurethane 
foam coatings or other spray coated layers, in uniform thicknesses in 
field applications, such as roofing applications or pavement applications. 
As shown in FIGS. 1 and 2, spray applicator vehicle 1 includes frame 2, 
operator seat 5, steerable powered single wheel 50, two unpowered side 
wheels 4, swinging boom 18, transverse rail subassembly 23 and various 
associated parts of nozzle 62 attached to carriage plate 26. Motor 6 
drives sprocket 52 of chain 8 through gear reduction box 7 to provide 
vehicle motion via wheel sprocket 51. The operator steers the vehicle 1 by 
steering wheel 9, which moves steering linkage bar 57, thereby rotating 
wheel flange 58. Boom 18 is continuously reciprocated from pivot point 20 
on tower 55 by crank arm 16 which is cyclically moved by reduction gear 
box 13 powered by motor 12, via adjustable linkage arm 14. Linkage arm 14 
is attached to output shaft 17 and is rotated at a constant speed as 
determined by settings in control box 11. Slot 15 permits adjustment of 
the lateral movement limits of telescoping end 19 of boom 18. Rails 24 and 
25 constrain the movement of carriage plate 26 to a linear path transverse 
to frame 2. 
Control box 11 also sets the ground speed of vehicle 1. Hose 35, which may 
consist of two or more separate hoses or individual lumens, carries liquid 
materials for spraying through nozzle 62 from a remote pressurized source. 
For polyurethane foam, two chemicals supplied from separate hoses 35 are 
mixed at the nozzle 62 just prior to discharge. The two liquids interact 
chemically causing an exothermic foaming and hardening reaction. Hose 35 
is retained in boom bracket 37 and may also be attached in one or more 
places by hook and loop straps 36. In normal use, a second (non-riding) 
work person guides hose 35. Solenoid 38, actuated by a switch in control 
unit 11, operates the discharge valve at nozzle 62. 
It can be appreciated that vehicle 1 rolling at a constant speed with boom 
18 reciprocating continuously is able to spray a continuous strip of 
coating on a surface. If the discharge rate at the nozzle is held 
constant, the amount of product sprayed on a surface per unit of sprayed 
area can be set by selecting ground speed. 
Since the boom changes direction at the distal ends of its swings, a method 
is employed to limit the amount discharged to prevent "double coating" at 
the edges. 
As noted before, prior art systems, such as described in Bellafoire '973 
and of. Autofoam.RTM. Company, shut the nozzle off at these portions of 
the cycle. However this action causes several problems. 
For example, the on/off cycling has detrimental effects on spray material 
consistency from a chemical reaction point of view. The on/off cycling 
also causes mechanical wear and induces metal fatigue on brackets that 
must react to cyclic pressure loading. 
In contrast to the devices of Bellafoire '973 and of the Autofoam.RTM. 
Company, the present invention uses a geometric arrangement and constant 
liquid product flow to prevent pattern edge build-up. 
For example, FIG. 3 shows a cross section of rails 24 and 25 in the middle 
of the transverse sweep. Carriage plate 26, driven by end bushing 27 on 
telescoping extension 19, is shown with brackets 65 and 66 attached. 
Brackets 65 secure top rollers 29 with concave "hourglass" contours. 
Similarly contoured bottom rollers 53 are secured by brackets 66. Thus 
rollers 29 and 53 capture rails 24 and 25 constraining plate 26 to roll 
along these rails. Plate 26 also supports nozzle holder assembly 34 (not 
shown in this figure). 
FIG. 4 shows an end view of rail subassembly 23. Both rails 24 and 25 are 
curved at their distal ends in a constant radius. Nozzle assembly 34 is 
shown in a flat vertical spray location at "A" and at an oblique spray 
location at the extreme limit of travel on the curved portion at "B". Top 
rollers 29 and bottom rollers 53 are offset from each other to facilitate 
easy rolling without binding on the curved portions. If boom 18 is 
reciprocated at an essentially constant rate, the carriage assembly is 
accelerated at the ends of travel due to the greater distance traveled per 
unit time on the curved end contour as well as the change in direction. 
Furthermore, the angle of nozzle 62 is tilted outward at the end so that 
the coverage area "BB" is larger than that of "AA". These end factors 
combine to reduce the thickness of the sprayed layer so that the "double 
layering" at the edge of each applied band of foam can be controlled to 
result in an edge thickness essentially the same as that of the center 
portion of a pass. This can be adjusted empirically based on the 
particular batch, temperature and other field conditions. The adjustment 
is the end limit position of nozzle 62 relative to the track end curve as 
determined by the adjustment of crank arm 16 in slot 15 of linkage arm 14. 
Spray vehicle 1 is designed to be easily disassembled into four 
subassemblies for easy transport to the roof of a building on an elevator 
or by using a winch. Prior art systems require a crane. Booms 18 and 19 
can be lifted off as a unit by removing spring pin 22 from upright link 
54, spring pin 21 from pivot shaft 20 and spring pin 28 from carriage 
plate 26 coupling. 
A front subassembly including of track subassembly 23 with uprights 3 can 
be removed by removing two spring pins 30 from frame member 2. 
Central frame 2 subassembly including wheels 4 can be separated from the 
driven wheel subassembly (including seat 5 and steering wheel 9 by 
removing large spring pin 60 from socket member 59 on the frame 
subassembly. Then back chassis 10 can be lifted free. Electrical 
connections tying the various subassemblies have connectors which must be 
disconnected. The four subassemblies can then be reassembled on the 
rooftop. 
FIG. 5 shows a block diagram of the electrical system largely housed in 
control box 11. The spray applicator vehicle 1 is electrically operated by 
connection to standard AC mains (typically 115 VAC at 60 HZ) via plug 40 
and extension cord 39. A portable engine operated generator can supply 
this power as an alternative. Although two separate modular AC/DC 
converters 76 and 83 are depicted, a single converter can supply current 
to all DC loads. 
An AC power switch 75 controls power to the entire spray applicator vehicle 
1. Converter 76 supplies DC to a unidirectional speed control 77 with 
digital speed indicator 78 and speed set control 79. For maximum 
consistency of application, speed control 77 is preferable a PID type of 
feedback servo control which maintains output speed of motor 12 (for 
swinging of boom 18) constant via feedback from encoder 80 mounted on 
motor 12. 
Switch 81 controls power to a solenoid 82 which opens the discharge valve 
at nozzle 62. Converter 83 supplies DC power to a bidirectional PID speed 
control 84 with digital speed indicator 85 and speed set control 86. This 
control accurately and repeatedly maintains the ground speed in either 
direction of spray applicator vehicle 1 as set even under varying load 
conditions by virtue of feedback encoder 87 mounted on motor 6. 
This operation is used during the spraying operation and determines the 
thickness of the resulting sprayed layer. Control switch 89 determines the 
direction of movement as forward or reverse. 
A second manual bi-directional speed control 90 is used to quickly select 
the desired ground speed via alternate manual control 91 when it is 
desired to maneuver spray applicator vehicle 1 prior or after a spray 
application. 
In this manner, the carefully selected "automatic" setting for spraying is 
not altered. Either automatic speed control 84 or manual speed control 90 
is actively enabled at any one time via selector switch 88. 
The repeatable application of a desired amount of coating per pass permits 
the type of roof foam surfacing depicted in FIG. 6. This is an exaggerated 
cross section of the end of a roof 61 surface with a central drain 96 
ditch with grate cover 95. If the roof 61 had a flat pitch, it would be 
desirable to create a pitch toward the drainage ditch for more effective 
drainage. This can be approximated by a stepped foam layer as shown, 
starting from lowest strip "A" and rising in thickness to strip "E" of the 
thickest cross section farthest from central drain 96. These strips can be 
applied in a single pass or in multiple passes by spray applicator vehicle 
1 where the ground speed for layer "A" is fastest and the speed is reduced 
for each successive layer "B", "C", "D" "E" and "F". 
For safety reasons, federal OSHA occupational safety regulations stipulate 
that a powered vehicle cannot be ridden by a workperson within ten feet of 
the edge of a roof. Also, a workperson is required to guide hose 35 while 
the operator rides and guides spray applicator vehicle 1. For these 
reasons, it would be desirable to operate spray applicator vehicle 
remotely. In this manner, a single workperson controls spray applicator 
vehicle 1 and guide hose 35. 
FIG. 7 shows such a remote control configuration. Control box 11 is 
replaced by a hand-held remote control box 100 with a face plate and 
several vehicle mounted functional units. Since the operator is no longer 
physically on spray applicator vehicle 1, electric steering ram 102 
replaces the steering wheel. Electric steeling ram 102 is controlled by 
positional steering control 101, which sets the position of steered wheel 
50 to match that of steering control wheel 106 on remote control box 100. 
Communications between remote control box 100 and spray applicator vehicle 
1 is via coiled cable 105, although a fail-safe radio communications 
channel can be used as well. To limit the number of individual conductors 
in cable 105, a multiplexor/demultiplexor module 103 and 104 is used at 
each end of cable 105 to facilitate the two way communications. The 
function of similarly numbered components is the same as that explained 
above in reference to FIG. 5. 
Hollow-cone nozzle 62 sprays a pattern 110 that impinges on the ground as 
shown in FIGS. 8 and 8A. As this pattern is swept sideways in a single 
pass, it will lay material that is denser toward the top and bottom edges 
resulting in a cross section with ridges 111 and valley 112 in the "Y" 
direction from roof surface 61. 
While multiple sweeps by boom 18 mitigate this effect somewhat, ridges in 
the final sprayed surface still persist. This problem is eliminated by 
nutating or cyclically rocking the nozzle mount 34 slightly at right 
angles to rails 24 and 25 several times during each sweep to even out the 
coverage of hollow-cone nozzle 62 over multiple sweeps. 
FIGS. 9A and 9B show optional modifications to accomplish this. The detail 
of FIG. 9A shows modified bracket 120 with pivot 121 holding nozzle mount 
34. Bracket 120 is fastened to carriage plate 26. A push-pull cable 
assembly including armored housing sleeve 123 with cable 122 within is 
used to actuate the cyclic motion illustrated by the phantom 
representation (shown in broken lines) of nozzle holder 34 at the extreme 
outward position. The detail of FIG. 9B shows the powering end of cable 
122. Bracket 126, attached to the frame of vehicle spray applicator 1 in 
the vicinity of gear box 13, retains sleeve 123. Cam follower 130 is 
pivoted at pivot point 128 within adjustment slot 127 and is biased toward 
multiple lobe cam 131 by spring 129. The stroke of wire 122 (and therefore 
the amount of cyclic tilt of nozzle holder 34) is determined by the 
dimensions and geometry of cam follower 130 and the depth of lobes on 
multiple lobe cam 131. 
The proper centering of the motion of holder 34 is adjusted by moving pivot 
128 within slot 127. Multiple lobe cam 131 is attached to the output shaft 
of gear box 13 under arm 14. It can be appreciated that cable wire 122 is 
cycled by each cam lobe as multiple lobe cam 131 rotates. 
By moving cam follower 130 out of contact with multiple lobe cam 131 and 
tightening it in a locked position, to defeat the pivoting, nozzle holder 
34 can be locked in a vertical position to defeat the nutating feature. 
Alternatively, a separate small gear motor and crank coupling (not shown) 
mounted right on bracket 120 can be used to actuate the nutating action 
without need of cable 122. 
Spray applicator vehicle 1 is easily modified to adhesively bond sheet 
elastomeric roofing material. As shown in FIG. 10, side arms 141 are 
pivoted at pivot point 140 from side extensions (not shown) which are 
attached to frame 2. These arms 141 have telescoping extensions 142 which 
are locked with hand screws 143. A roll of elastomeric sheet 144 is 
pivoted at the end of arms 142 at pivot point 148, with sheet end 145 
trailing roll 144 as vehicle spray applicator 1 moves in the direction of 
arrow 149. Also pivoted at pivot point 148 are side arms 146 which trail a 
weighted roller 147, which weighted roller 147 applies even pressure to 
sheet layer 145. Nozzle 62 sprays a layer of bonding adhesive which bonds 
sheet 145 to roof surface 61. 
Alternately, roll 144 can be adjusted to apply a skin coating of rolled 
material over the solidified foam layer applied from nozzle 62 to a 
surface, such as a roof. 
Adjustment of extensions 142 determine the distance X between the sheet 
contact and the sprayed roof surface a fixed distance from the center of 
the spray cone. Since the vehicle moves at a predetermined constant speed, 
distance X can be used to match the optimal delay from adhesive 
application to contact of the sheet roofing material. 
A method for applying reinforced foam roofing involves the use of a 
reinforcing fabric or open fabric mesh. The fabric can be manufactured of 
a variety of fibers such as nylon, fiberglass, aramid, etc. The method 
involves spraying a foaming mixture and immediately imbedding the 
reinforcing fabric in the mixture before the foam rises so that the 
reinforcing fabric rises with the foam and is embedded in the foam layer. 
FIG. 11 shows modifications of the spraying applicator vehicle 1 for 
accomplishing this task. Side arms 160 are rigidly attached to frame 2 and 
uprights 3; they flare out at the distal end to lie outside of the spray 
pattern on each side. Roll 164 of lightweight reinforcing fabric is 
pivotly attached at the end of arms 160. The free end of fabric 165 is fed 
under light roller 162, which contacts surface 61 just at the edge of the 
foam adhesive spray pattern. Spring plunger 161 supported by brace 163 
forces roller 162 into contact with roof surface 61. Foam spray 168, prior 
to rising, is contacted with fabric 165, which rises with foam 166 to 
embed itself in the foam layer as shown by the broken line. 
It is further noted that other modifications may be made to the present 
invention without departing from the scope as noted in the appended 
claims.