Note: Descriptions are shown in the official language in which they were submitted.
10~1856
This invention relates to a spray gun for simul-
taneously spraying a liquid and a particulate material such
as dyed sand, for example in applying decorative facings to
walls and like surfaces.
According to the invention the gun includes a
body defining a handle section and a nozzle assembly coupled
to the body and having a central opening for the discharge
of a stream of said particulate material and liquid dis-
charge menas disposed around said opening for the discharge
of liquid around said stream of particulate material. The
body includes a first air passageway adapted to be supplied
; with pressurized air and coupled to said central opening
of the nozzle assembly. A second air passageway is also
provided and is adapted to be supplied with pressurized
air and is coupled to said liquid discharge means of the
nozzle assembly. First liquid inlet means is provided for
the introduction of said particulate material into the first
air passageway. Second inlet means is also provided, through
i which said liquid can be introduced under pressure into the
second air passageway and the body also includes means for
controlling the introduction of said particulate material
into the first air passageway. The gun has a trigger
mounted on the body adjacent the handle section for pro-
gressive movement with respect to said body from a rest
position, the trigger being positioned so that it can be
squeezed towards said handle section by a person holding
the gun by said section. Spring means is provided normally
biassing the trigger to its said rest position. An air flow
control valve is disposed in the first air passageway and
is coupled to the trigger so that the valve is progressively
opened as the trigger is squeezed. The second inlet means
~3` - ~
~ 1071856
` ' .
includes a liquid flow control valve coupled to the
trigger so as to be progressively opened as the trigger
is squeezed. This allows the volume of liquid and the
amount of particulate material issuing from the gun to
be simultaneously varied in use by operation of the
trigger.
- The invention will be better understood by
reference to the accompanying drawings which illustrate
various embodiments of the invention by way of example.
In the drawings:
Fig. 1 is a schematic plan view of a sand
dyeing installation for performing the process according
to the invention; --
Fig. 2 is an end view of a typical one of the
tanks in the installation of Fig. l;
Figs 2a is a detail perspective view of part
of Fig. 2;
Fig. 3 is an exploded diagrammatic perspec-
tive view of one of the ovens of Fig. l;
Fig. 3a is a detail view of part of Fig. 3;
- Fig. 4 is a vertical sectional view through
a spray gun which may be used to apply to a surface
dyed sand produced in the installation of Fig. l;
Fig. 5 (which appears on the same sheet as
Figs. 2 and 2a) is a front view of the spray gun of
Fig. 4; and,
Fig. 6 is a diagrammatic illustration of -
a paint and air supply system for the spray gun of
Figs. 4 and 5.
.
; ` lOql856
.
~ The invention has been devised primarily
,~ in connection with the dyeing of waste sands (called
tailings) derived from the Athabasca Tar Sands pro-
ject in Alberta. It is however to be understood that
~; the method may be used to dye other sands.
, Typical samples of tailings used in the
, method of the invention have the following charac-
teristics.
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Referring now to Fig. 1, the various components
of a sand dyeing installation are indicated in diagrammatic
form. The installation includes a sand pit 20 which contains
sand to be dyed. Successive batches of sand are conveyed
from the sand pit 20 through various treatment stations to
` be described, to a bagging plant 22 located at the end of
the installation remote from the sand pit 20. The succes-
sive batches of sand are conveyed from the sand pit to
the bagging plant by a conveyor device comprising a series
of individual conveyor sections 24 arranged between the
respective components of the installation and arranged to
convey the batches generally in a rectilinear direction
from the sand pit 20 to the bagging plant 22. Each section
is in the form of a conventional belt conveyor. --
Arranged at spaced intervals along the conveyor
path are three ovens 26, 28, and 30. A typical example
of one of these ovens is illustrated in Fig. 3 and will be
more specifically described later. The first oven 26 is
~' positioned adjacent to and spaced from the sand pit 20. A
screening plant 32 is positioned downstream of the oven 26
,
~ 20 in the direction of sand travel. From the screening plant
, .
32 the sand passes to a first washing tank 34 and from ~
3 there to one of two dyeing tanks 36, 38. The second oven
28 is positioned downstream of the two tanks 36, 38. Posi-
' tioned intermediate the second oven 28 and the third oven
30 is a second washing tank 40. A final screening plant 42
~ - - .
is positioned downstream of the third oven 30 and in
advance of the bagging plant 22.
The components described above form the main
treatment stations of the installation. Associated with
7--
` -` 1071856
.
the main components are a number of auxiliary components
which will now be described. These auxiliary components
include a series of fifteen separate dye holding tanks
generally indicated at 44. The tanks contain batches of
dye solutions having respectively different characteristics.
For example, the tanks may contain dye solutions have re-
` spectively different colours or shades of colour. The
tanks 44 have individual outlet pipes generally indicated
at 46 which are connected to a common line 48 coupled to
' 10 both dyeing tanks 36, 38. A common return line 50 extends
, from both dyeing tanks 36, 38 and is coupled to each of the
dye holding tanks 44 by suitable valves.
It will be convenient at this stage to note that
the various valves used in installation are generally de-
noted by the letter v. The valves are conventional liquid
flow control valves and may be manually or automatically
; operated. Similarly, the various pumps employed in the
installation are denoted by the letter P. The pumps are
also conventional pumps used for conveying liquids.
Referring to the dye holding tanks 44, it will
be appreciated that the valving arrangement is such that
an individual tank or group of tanks can be coupled to
- either or both of the dyeing tanks 36, 38. Also, unused
dye solution can be returned from one or both of the dyeing
tanks to the relevant dye holding tank or group of tanks.
The dye return line 50 is also provided with a drain 52
through which waste dye solution can be removed from the
return line if necessary.
Each of the dye holding tanks 44 is provided
with a heating element 54 in the form of a convoluted water
_ ~ _
`, lQql856
` pipe arranged inside the tank. These heating elementq
allow the temperature of the dye solution in each tank
to be controlled in accordance with the requirements of
the dyeing process. The heating elements 54 are coupled
with a hot water boiler 56 by way of flow and return
lines 58. It will be noted that the individual tanks
are coupled to the lines 58 by valves so that the heating - -
elements 54 can be individually controlled. The return
line to the boiler includes an expansion tank 60. The
flow line includes a solenoid operated valve 62. Each - -
of the dye holding tanks is fitted with a thermostat 64
; coupled with valve 62 such that-the valve is shut off and
the flow of hot water to the heating elements 54 is
terminated when all of the tanks reach a predetermined
temperature.
- - The boiler 56 is also coupled by lines 66 with
- a hot water tank 68. The relevant line 66 is provided
with a solenoid operated valve 70 similar to valve 60
and controlled by a thermostat 72 in tank 68. Tank 68
`!' 20 provides a hot water supply for the washing tank 34 and
is coupled to the tank by a line 74. Water leaving the
washing tank 34 is delivered to one of two sumps 76, 78
which are separated by a filter 80 consisting of rock,
gravel and sand. Water entering the sump 76 from tank 34
passes to sump 78 by way of a filter which removes coarse
elements and impurities. Sump 78 is connected to the
hot water tank 68. It will be appreciated that the arrange-
ment just described provides a facility for hot washing of
sand in the tank 34.
A somewhat similar arrangement is provided in
. .
_ g
10~1856
association with the second washing tank 40, but in this
case cold water is used. Tank 40 is coupled with two
sumps 82, 84 separated by a filter 86.
The washing tanks 34 and 40 and the dyeing
tanks 36 and 38 are all of the same general construction.
Fig. 2 shows a typical example of one of these tanks.
The tank is open topped and is of rectangular shape in
plan view having downwardly and inwardly inclined opposite
sides 88 and upright end walls 89 (only one of which is
visible). Rotatably mounted in the bottom of the tank
are three spiral screws 90. As can be seen the tank
bottom is shaped to define semicircular troughs in which
the screws rotate. The screws are continuously driven
in rotation by motors (not shown) in the directions indi-
cated by the arrows. It will be noted that the two outer
screws rotate in the same direction whereas the centre
screw rotates in the opposite direction. These screws
serve to mix the contents of the tank during the dyeing
process.
The tank is provided with liquid inlet and outlet
pipes denoted respective-ly 91 and 92. Valves control
liquld flow to and from the tank through these pipes,
although these valves are not shown in Fig. 2. The inlet
pipe 91 opens into the wall of the tank which is shown
at the far end in Fig. 2. The outlet pipe 92 opens into
the opposite end wall 89 adjacent the lower end of the wall.
Fig. 2a shows the inner end of this pipe. The pipe is
fitted with a filter (not shown) to restrict entry of
sand. Liquid entry is controlled by a valve member 93
having a front face 94 which is positioned across the
-- 10 --
`` ` 1071856
:. ' '
open inner end of pipe 92 when the valve member is in
the closed position in which it is shown in Fig. 2a.
Referring back to Fig. 2, valve member 93 is
vertically movable between guide plates 95 from the
closed position in which it is shown, to an upper position
clear of the pipe 92; in this position liquid can enter
the pipe. Vertical movement of the valve member is
~- effected by a pneumatic piston and cylinder unit 96.
'~ Air is delivered to the unit from a conventional air
pressure source. Admission of air to the unit and exhaust
- of air therefrom is controlled'by conventional manually
operable pneumatic valves (not shown). --
' -It will be noted that the lower portion 97 of
, . .
the valve member 93 is of inverted, generally triangular
shape'in end view and has a lower edge 98 which is'in- ' - -
' clined upwardly away from face 94. When sand is present
in the tank and the valve member 93 is in its closed
.
; position, the lower portion of the valve member produces
~ .
- in the sand, a molded depression, the bottom of which is
downwardly inclined generally towards the outlet pipe 92.
Accordingly, when the valve member is raised to expose
` the pipé 92, the depression at least substantially remains
and acts as a trough which serves to aid liquid flow into
` the pipe 92.
Sand is removed from the tank through a "trap
door" formed by a hinged section 99 of the bottom of the
tank. This section is formed in the part of the trough which
- - receives the centre screw 90. The section is of a length
less than that of the screw and is movable between the
closed position which it is shown in Fig. 2 and the open
-- 11 --
;` ` 1071856
.. ` ` .
position indicated in chain line. Movement of the sect-
ion 99 between its open and closed positions is controlled
" by a pneumatic piston cylinder unit 100 mounted adjacent
the tank. As in the case of piston cylinder unit 96,
unit 100 is supplied with air from a conventional source
and is controlled by manually operable pneumatic valves
(not shown). Of course, either of the pneumatic piston
and cylinder units could be replaced by hydraulic units in
other embodiments of the invention.
In use, liquid (water in the case of the washing
tank 38 and 40, and die solution in the case of the
dyeing tank 36 and 38) enters the tank through inlet
pipe 91. Sand is then delivered into the tank by the
relevant conveyor section 24. The screwsserve to agitate
the sand and ensure thorough mixing with the liquid. The
valve member 93 is of course in the closed position at
this time. When the sand and liquid are to be separated,
~ - the valve member 93 is raised to its upper position, ex-
- posing the pipe 92 and allowing the liquid to drain from
the tank. The valve in the liquid inlet pipe 91 is of
course closed at this time. When all the liquid has been
drained from the tank, the hinged section 99 of the tank
,
; bottom is moved to its open position and the screws 90
are operated to discharge the sand from the tank. The
tank is positioned directly above the relevant one of
- the conveyor sections 24 so that the discharged sand falls
directly onto the conveyor.
Reference will now be made to Fig. 3 which
schematically illustrates one of the ovens 28 and 30 of
Fig. 1. The first oven 26 is also of basically similar
.,
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- ` - 12 -
:
1071856
` '
form; its construction will also become apparent from
the following description of Fig. 3. It should be noted
that, for clarity of illustration, the base of the oven
and the support and drive structures for various compon-
ents have not been illustrated.
The oven shown in Fig. 3 includes a belt con-
veyor generally indicated at 104, having a belt made of
a woven metal mesh. The belt is heated by gas flames.
Air is blown over the sand on the conveyor by a blower
generally indicated at 106 fitted to the oven housing 108.
Sand is delivered to the end of the conveyor 104 which is
shown at the left in Fig. 3 by way of a delivery device
110 and leaves the oven by way of a rubber roller crusher
112 adjacent the opposite end of the belt conveyor. The
first oven 26 of Fig. 1 differs from the oven shown in
:- .
Fig. 3 only in that oven 26 has no rubber roller crusher
' 112; otherwise, the oven 26 is as shown in Fig. 3.
~ ~ .
Belt 114 of the conveyor 104 travels around four
rollers 116, 118, 120 and 122 which are mounted to rotate -
about parallel longitudinal axes. All four rollers are
simultaneously driven in the same dlrection from a common
shaft by individual worm and wheel drives (not shown).
Considering the oven from the position of Fig. 3, the
-~ rollers 116 to 122 rotate clockwise. Welded to the inner
` surface of the belt are two parallel endless chains 124,
126 which are spaced transversely of the belt. Each roller
116 to 122 has two series of peripheral teeth which engage
~ with the respective chains 124, 126 for driving the belt.
- ~o of these series of teeth are indicated at 130 and 132
~ 30 in association with roller 118 although it is to be understood
. ~ , ' .
- 13 - -
' .
- . :.
~ ` 10~1~356
that all four rollers have similar teeth. The lower run
of the belt 114 is supported by a series of idler rollers
134, 136, 138. In addition, an adjustible roller 140 is
provided adjacent the roller crusher 112 for the purpose
of adjusting the tension in the belt.
Three rollers 144, 146, 148 are positioned below
- and in contact with the upper run of the belt 114 inter-
mediate the rollers 116 to 122 for vibrating the belt.
Each roller 144, 146, 148 has reduced diameter portions at
ro the positions of the chains 124 and 126. The reduced
diameter portions of roller 146 are indicated at 150 and
152; similar portions are provided on the other two rollers.
Each vibrator roller 144, 146 and 148 is provided with
three longitudinally spaced series of rods. Each series
includesfour such rods circumferentially spaced around the
~ roller. Fig. 3a is a vertical sectional view through
.
roller 146 and shows the rods (154) in one of these series.
For convenience of illustration, neither the rods 154 nor
~ . . .
,~,
the corresponding rods of rollers-144 and 148 are shown
in Fig. 3. The rods 154 are of cylindrical shape and
are mounted in recesses in the roller surface so as to be
individually rotatable about axes parallel to the axis of
the roller. The rods protrude -rom the surface`of the
roller so that, when the roller rotates, the rods move
successively into contact with the undersurface of the
belt; since the surface portions of the roller between
the rods are lower than the rods, this causes the belt to
vibrate. The vibrator rollers 144, 146 and 148 are driven
from a common drive shaft by individual worm drives (not
` 30 shown). The worm drives are arranged so that the frequency
- 14 -
1~7i856
of vibration imparted to the belt increases from roller
144 to roller 148 whereby sand on the belt is subject
to progressively greater vibration as it approaches the
roller crusher 112.
Associated with vibrator roller 148 is a
screen crusher in the form of a roller 162, the
curved surface of which is formed by a mesh screen 164.
The roller is driven by contact with the belt 114 and
rotates about an axis parallel to roller 148. The
vibrator rollers 142, 146 and 148 together with the
screen crusher 162 serve to spread sand evenly on the
surface of the belt and to break up cohesive clumps of
sand.
When the ovèn is in use belt 114 is heated by
gas flames which play on the undersurface of the upper
run of the belt. The flames emanate from gas manifolds
166, 168, 170, 172, 174 and 176 positioned below the
upper surface of the belt and connected to a common gas
supply (not shown). Each manifold is fitted with an
array of upwardly directed gas jets 178. The gas jets pro-
duce a temperature in the approximate range 250 to 350F
when the oven is in use. However, it has been found that
the colour the dyed sand can be lightened by increasing
, .
the temperature above this range in oven 28 and/or in
;~ .
-~ oven 30.
~, .
The sand supply device 110 includes a pair of
inclined side plates 180, 182 which together define a
trough. The plates are flexibly mounted and each is
fitted with two vibrators such as thoseindicated at 184,
- 30 186 in association with plate 180. Sand is delivered
:j
- 15 -
.
~ ' .
~` 1C~71856
into the centre region of the device 110 through a shute
~ opening 188 in the casing 108. The sand is then spread
- outwardly from this central location by a screw 188
which extends longitudinally of the device 110. Screw
188 has flight sections 190 and 192 of respectively
opposite hand which cause the sand to be distributed longi-
tudinally of the device from the central location at
which the sand is delivered to the device. Arranged on
respectively opposite sides of the screw 188 are two belt
conveyors 194, 196 disposed in a V configuration and having
their lower ends closely spaced. Typically the width of
the longitudinal opening between the lower ends of the two
conveyors 194, 196 would be in the range 1/4 to 1/2 inch.
When the device 110 is in use, sand delivered
outwardly by the screw 188 falls down between the two
belt conveyors 194 and 196 and any clumps of sand are broken
up by the action of the conveyors. Smooth downward movement
of the sand is ensured by the vibrators on the plates
.
- 18~0 and 182.
The roller crusher 112 at the opposite end of
- the belt conveyor 104 includes two rubber rollers 198~ 200
mounted to rotate in a trough 202. The rollers 198 and
200 are arranged with their axes parallel to the axes of
the belt driving rollers 116 to 122 and are continuously
driven in opposite directions as indicated by the arrows
in Fig. 3. The roller crusher is arranged so that sand
leaving the discharge end of the belt conveyor 104 falls
generally into the nip between rollers 198 and 200 where-
by further spreading of the sand is effected. Trough
202 has a longitudinal discharge opening 204 through which
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;
. ~ ,
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" " 107i856
discharged sand falls onto the appropriate conveyor section
24 located below the oven.
As indicated above, the housing 108 of the oven
is fitted with an air blower 106. The blower includes a
casing 206 which supports a motor 208. The casing is of
cylindrical form and is open ended. A centrifugal impeller
210 is positioned in the opening and is driven in rotation
by the motor 208 so that air is drawn into the ends of the
- casing 206. Casing 206 has a tangential outlet 212 arranged `
` 10 inside the casing 108 so that air is directed downwardlyfrom the blower generally towards the upper run of the
belt 114 of conveyor 104. Casing 108 has an air outlet 213
adjacent the discharge end of the belt conveyor 104. Out-
let 213 communicates with a chimney 214 fitted with an air
filter 216.
Preparatory to the commencement of the dyeing
t process, batches of dye solution are prepared in appropri-
: `ate ones of the dye holding tanks 44. For example, if -`
only a relatively small amount of sand is to be dyed, it
- 20 might be necessary to use only a single one of the tanks
- 44. Alternatively, if a larger production is planned,
several of the tanks might be used and may be filled with
the same of respectively different coloured dyes.
~ Any appropriate water soluble dye may be used.
- Experience has shown that fabric dyes such as TINTEX, RITZ
or DYLON (registered trade marks) dyes are eminentlY suit-
- able for use in the process of the invention. TINTEX
powder dye has been found to be particularly effective.
~ Whichever dye is selected, it is preferably used at approxi-
; 30
.~1 ` '` , .
I - 17 -
1071856
mately double the strength recommended for dyeing fabrics.
The prepared batches of dye in the relevant
ones of the dye holding tanks 44 are then heated to approx-
imately 200F by means of a boiler 56. The thermostats
64 in the dye holding tanks 44 are ad~usted to approximately
this level. Similarly, the water in the hot water tank
68 is held at approximately 200F by thermostat 72. It
will be recalled that this water is used in the first wash-
ing tank 34. The water for the second washing tank 40
is contained in the sumps 82 and 84 and is at approximately
room temperature. Accordingly, a substantial temperature
differential exists between the hot water used in tank 34
~ and the cold water used in tank 40.
- The dyeing process can now proceed by transporting
a first batch of sand from the sand pit 20 to the first
oven 26. In passing through this oven, the sand is dried
and substantially uniformly distributed across the belt
conveyor in the oven. Drying takes place at a temperature
.
in the approximate range of 250 - 350F. Passage of the --
sand through the oven may also assist in removing from
~ the sand impurities such as tar. On leaving the oven,
the sand is conveyed to the screening plant 32. This plant
has not been specifically illustrated in-the drawings
- since it is a conventional installation for screening
particulate material. The plant is arranged to remove
material exceeding .300 mm in a diameter. This material is
conveyed from the screening plant by a conveyor indicated
at 218 and is delivered to a waste material pit 220.
Material passing through the screening plant 32
passes through the first washing tank 44 in which it is
; washed with hot water (200F) to clean the sand. The
.
- 18 -
-~ 10q1856
clean sand then passes to one of the two dyeing tanks 36,
; 38. Two tanks are provided in order that separate batches
of sand may be simultaneously dyed. The batches in the
respective tanks may be of the same colour or of respectively
` different colours. In any event, dye solution at approxi-
mately 200F is added to the sand in the relevant one of
` the tanks 36, 38. The sand and dye are agitated together
in the tank by the screws in the bottom of the tank (see
Fig. 2). The sand and dye are allowed to remain in contact
for approximately 1 hour.
^ At the end of the dyeing period, the dye solution
~; is pumped out of the dyeing tank and the sand is conveyed
to the second oven 28. In this oven, the sand is again
spreaa substantially uniformly across the belt conveyor
` and is vibrated as described in connection with Fig- 3.
In passing through oven 28, the sand is thoroughly agitated
- and dried. The temperature in the oven is in the approxi-
mate range 250 to 350F.
From oven 28, the sand is delivered to the wash-
ing tank 40 in which it is continuously washed with cold
- water from sump 84. The water is normally at ambient (room)
temperature. The washing process is visually supervised and
is continued until water leaving the washing tank 40 is
observed to be substant-ially clear. The sand is then conveyed
to the oven 30 in which it is again spread on a heated con-
veyor belt. Oven 30 dries the sand. Again, the temperature
in the oven is in the approximate range 250 to 350F.
Finally, on leaving the oven 30, the sand passes
to the screening plant 42. This plant is identical to
screening plant 32 and acts as a final filter to remove
-- 19 --
` `` 1071856
I
particles larger than .300 mm. These particles are
returned to oven 30 by way of a conveyor 222 for recycling.
In Fig. 3, numeral 224 indicates in chain line an opening
provided in the casing of the oven to receive these re-
` cycled particles. Screened material leaving plant 42 then
passes to a bagging plant 22 of conventional form.
As indicated above, the dyed sand is intended tobe used as a decorative facing material, for example, on
walls and like surfaces. For this purpose, the sand is
` 10 mixed with a binding material. An example of a suitable
material is polyurethane varnish. Another example is a
silicone binding material. The sand may be sprayed onto
a surface simultaneously with a polyurethane varnish which
will then dry, retaining the sand particles on the surface.
The-resulting facing is tough, durable and decorative.
Commercially available clear polyurethane varnish may be
`~ used for this purpose. A typical such varnish is sold
under the registered trade mark VARATHANE. An example of
another suitable varnish is sold under the trade mark
OCEAN FIRE. This varnish has fire retardant properties.
As indicated above, the varnish and sand are --
preferably simultaneously sprayed onto the surface to -
be coated. This may be effected by using two spray guns,
one for the varnish and one for the sand, or by means
of a single spray gun having a facility for simultaneously
spraying the varnish and sand. A suitable spray gun is
shown in Figs. 4 and 5 of the drawings. On the other hand,
for small scale uses, it would be possible to spray the
varnish from an aerosol or like container and manually dis-
pense limited quantities of dyed sand into the varnish
- 20 -
`' lOq~856
.
streamissuing from the aerosol. In other cases, sand
particles could be sprinkled onto a surface coating of a
binding material.
Referring now to Figs. 4 and 5, the spray gun has a
body which includes a handle section generally denoted 226
shaped to define a pistol grip 228. The gun also includes a
nozzle assembly generally denoted 230, which is fitted to
'~ the handle section 226. The nozzle assembly is in fact
made in two separable sections denoted respectively 232
and 234. The inner section 232 includes an upwardly di-
rected sand inlet 236 and a downwardly directed liquid
inlet 238. The gun has two air inlets, the inlets
being denoted respectively 240 and 242. As will
be more specifically described later, air introduced
through inlet 240 serves to propel sand entering the gun
- through inlet 236 and air entering through inlet 242 pro-
pels liquid entering through inlet 238.
The handle section 226 defines a forwardly
directed portion 244, the outer end of which is surrounded
by an annular rebate 246 which defines a projecting annular
central portion 248. The inner section 232 of the nozzle
assembly 230 defines a recess 250 of a shape complimentary
to the external shape of portion 248 of the handle section
226. It will be appreciated that section 232 is accord-
ingly separable from section 226. In the assembled gun,
the two sections are held together by retaining screws
(not shown). The outer section 234 of the nozzle assembly
is fitted into a recess 252 in the inner section 232 and
is retained in the recess by a part of the air inlet 242,
as will be described. Section 234 is visible in front
view in Fig. 5.
- 21 -
10~1856
` ' ' .
The handle section 226 is formed with an air
passageway which includes a first portion 254 extending
- through the pistol grip 228 from the air inlet 240 to a
valve assembly generally denoted 256. The air inlet 240
. includes a fitment 258 which permits an air hose (to be
described in connection with Fig.6) to be coupled to
passageway 254. The fitment 258 is in the form of screw
threaded sleeve received in a complimentary screw threaded -~
outer end portion of passageway 254. The sleeve has an
-` 10 integral flange 260 by which a sealing ring 262 is trapped
- against the lower end of the~pistol grip 228.
Valve assembly 256 includes a chamber 264 into
which passageway 254 opens. Chamber 264 is of cylindrical
shape and has an outer end closed by a screw 266 and a
sealing washer 268. The inner end of chamber 264 has a
- central opening 270 fltted with an annular valve seat ~--
272. The opening communicates with a second portion 274
of the air passageway in the handle section 226.
. , , :
~ A~control rod 276 extends axially of chamber 264 :
; 20 and through the opening 270. Rod 276 has an inner end
- portion which is received in a recess 278 in screw 266 and
an outer portion which projects from the handle section 226
for cooperation with a trigger 280 pivotally mounted on
the section. A conical valve member 282 is fitted to rod
276 and is normally biased into engagement with valve
seat 272 by a compression spring 284 on the inner end
portion of rod 276. Accordingly, the valve member 282
normally closes opening 270. Trigger 280 is formed from
sheet metal and defines two lugs 286 (only one of which is
visible) pivotally coupled to the handle section 226 of
.
~;
- 22 -
, . . .
'
- - ,
- .
lOql856
the gun. In the position in which the trigger is shown
in Fig. 4, rod 276 bears against the trigger and can
therefore be moved against the action of spring 256 by
squeezing the trigger. This causes the valve member
282 to lift off the seat 272 and bring passageway 254
into communication with passageway 274.
At its outer end, passageway 274 communicates
with a sleeve member 288 fitted in an opening in the
inner nozzle section 232. The main part of member 288
is cylindrical but the member also has an integral flange
289 of square shape. This flange is received in a
complementary recess in the nozzle section 232 so that
the member 288 cannot turn. Member 288 has an axial
passageway 290 of small diameter, which communicates in-
side section 232 with a chamber 291 coupled with the
- sand inlet 236. As a result of the small diameter of
passageway 290, the velocity of air entering chamber 292
when the gun is in use, is increased compared with its
velocity in passageway 274. A needle valve 292 (see
also Fig. 5) is provided in the nozzle section 232 and
can be used to restrict passageway 290 and hence control
^; the air flow along the passageway when the gun is in use.
Valve 292 is screw threaded into the nozzle section 232
- and has an external head 293 (Fig. 5) by which the valve
can be turned to control said air flow in use.
The outer nozzle section 234 includes a sleeve
294 having an axial passageway 295 arranged in alignment
., .
- with passageway 290. Sleeve 294 is-received in an elongate
recess 296 in section 234, which recess opens into the
outer end of section 234. The outer portion of recess 296
and the corresponding part of sleeve 294 are both of cylindrica
- 23 -
.
'lOql856
cross-section. However, the inner portion 297 of sleeve
294 is square as is corresponding part of recess 296 and
the part of the chamber 291 into which sleeve 294 extends.
This prevents the sleeve turning inside the nozzle section
234.
Sand is delivered to the inlet 236 from an in-
verted container 298 which is held in position on the
inlet by a ring clamp 299. The container has an open top
for filling purposes and is fitted with a handle (not
shown) by which the container can be steadied during spray-
ing. When the gun is in use, sand falls down through inlet
' 236 into chamber 291 under the action of gravity. The
- flow of sand can be controlled by a valve 299 turnably
mounted in inlet 232 and operable by an external knob 300
(Fig. 5). Valve -299 is formed with a transverse passageway
301 through which the sand flows. High velocity air
entering chamber 291 from passageway 274 propels the sand
particles along the passageway 295 in sleeve 294 and out
; of the gun in a stream.
~ 20 Liquid varnish is delivered to the nozzle
. , .
assembly 230 and issues from the gun simultaneously with
the coloured sand. As will be described, the liquid enters
the nozzle assembly from inlet 238. The sleeve 294 of the
nozzle assembly is formed with an external annular recess 302
into which liquid droplets pass from inlet 238. Six
V-section grooves 303 (see Fig. 5) are formed in .he outer
portion of the surface of nozzle section 234 which defines
recess 296 and extend from the position of the recess 302
to the exterior of section 234. As can be seen from Fig.
30- 5, these passageways are equally spaced around the outer
i .
- 24 -
lOql8~6
end portion of nozzle sleeve 294. Accordingly, the liquid
issues from the nozzle assembly in six fine streams
, arranged in an annular configuration around the stream of
sand issuing from passageway 295. The liquid streams
- are generally indicated 304 in Fig. 4.
It will of course be appreciated that the outer
nozzle section can be replaced by a section having grooves
` 303 of a different number, size or distribution in order
to vary the characteristics of the liquid spray. In fact,
nozzle assembly could be designed to provide an annular -
; .
gap through which the liquid would issue in an annular
"curtain" around the steam of sand.
The liquid varnish is delivered to inlet 238
` under pressureas will be described in connection with
Fig. 6. As in the case of the air inlet 240, inlet 238
includes a fi'tment 308 in the form of a screw threaded
:-. . . . .
'-~ sleeve to which the supply~line is coupled. Fitment 308 is
', screwed into a complimentary screw,threaded opening in a - -
~ depending portion 310 of the inner nozzle section 232,
... .
,- 20 This opening communicates with a longitudinal passageway
' 312 in the said portion 310. Opposite ends of the passage-
way are closed by plugs 314 and 316. A valve 317 is pro-
- vided in the inlet fitment 308 to control the flow of
liquid into the gun in use. The valve is in the form of
a simple turnable spindle having an external head (hidden
., .
in Fig. 5) and formed inside the fitment with a diametral
opening 319 which can be aligned with the passage in inlet 308.
By turning the spindle head, it is possible to vary the
position of the opening 319 in relation to the axis of
the fitment 308 and hence control the volume of liquid
entering inlet 308 in use.
,
- 25 -
!
" 10'71856
The second air inlet 242 also communicates with
the passageway 312 referred to above. This inlet also
includes a sleeve 320 having an outer screw threaded por-
tion 321 by which an air line can be coupled to the inlet
in use. The inner portion 322 of sleeve 320 is extended
compared with the sleeves of the other inlets and has a
- screw threaded inner end portion which is received in a
complimentary screw threaded opening in the outer nozzle
section 234. It will be appreciated that sleeve 320 accord-
ingly serves to retain section 234 in position. It will
also be noted that the internal passageway in sleeve 320
communicates with the annular recess 302 of the sleeve 294
of the nozzle assembly. The passageway in sleeve 320 also
communicates with passageway 312 by way of openings 324.
Inlet 242 is also provided with a needle valve generally de-
noted 325 similar to the needle valve 392 referred to above. --
Valve 325 can be used to regulate the air entering the
spray gun through inlet 242.
When the gun is in use, air entering inlet 242
flows through sleeve 320 and mixes with liquid entering the -
sleeve under pressure through openings 324. Delivery of
liquid into the air stream in sleeve 320 is controlled by
a needle valve in passageway 312. The valve includes a-
needle 326 which is biased to the right in Fig. 4 by a spring
328 extending between plug 314 and a collar on the needle.
An annular seal 329 is provided on the needle to prevent
leakage of varnish. When the needle valve is closed, the
inner end of the needle fits into the central opening of an
annular member 330 positioned inside passageway 312 between
inlet 238 and inlet 242. It will be appreciated that some
- 26 -
,
- l~ql856
atomization of liquid will occur as the liquid passes
through the central opening in member 330 and that further
atomization will occur when the liquid meets the air
stream in sleeve 320. The outer end of needle 326 is coup-
led to a rod 332 which extends through an opening 334 in
the trigger 280. As can be seen, the outer end portion
of rod 332 is bent downwardly to a slight extent as indicated
at 336. Two holes are provided at spaced positions along
portion 336. A spring clip 338 is intended to be inserted
; 10 into a selected one of these holes to couple rod 332 to
the trigger 280 so that the needle valve can be opened by
squeezing the trigger 280.
In the position shown in the drawings, clip 338
' is inserted into the hole nearest the outer end of rod
332 so that when the trigger is squeezed both the liquid
needle valve 326 and the air control valve 256 will be
opened. Accordingly, sand and liquid will be simultaneously
delivered through the nozzle of the gun. If the rod 332 is
turned to bring its outer end portion 336 to the upwardly dir-
ected chain line position indicated in Fig. 4, clip 338
can be inserted into the other of the holes in portion 336,
bringing the trigger to the chain line position indicated
~ at 280'. In this position, operation of the trigger will
- not affect the valve 256 so that liquid only will be de-
livered to the nozzle. If the gun is to be used for
spraying sand only, clip 338 can be removed entirely, in
which case valve 256 only will be operated. It will of
course be appreciated that it will not normally be necessary
to spray sand or-liquid alone in applying decorative facings.
Fig. 6 shows the paint and air supply system for
the spray gun of Figs. 4 and 5. It will be remembered that
- 27 -
10~1856
the spray gun has a liquid varnish inlet fitment 238
and two air inlet fitments 240 and 242. In Fig. 6 unions
for coupling to said fitments are indicated respectively
at 340, 342 and 344. Union 340 is coupled to a supply of
liquid varnish under pressure. Unions 342 and 344 are
coupled directly to a pressurized air supply.
Numerals 346 and 348 denote pressurized air
supply lines controlled by individual pressure regulators
350 and 352 respectively. The pressurized air supply
delivered to lines 346 and 348 is derived from a common
compressor represented generally by the box denoted 354.
Of course, individual compressors could alternatively be
used. Air supply line 346 is coupled to the union 342
for the air supply inlet 240. The regulator 350-is
arranged to produce an air pressure in the ran~e 40 to 50
p.s.i.
The other air supply line 348 is coupled to one
limb of a T-peice denoted 356. Air line 248 is connected
, . .
to one horizontal limb of the T piece. The other limb is - -
connected to an air line 358 having at its outer end the
union 344 for connection to air inlet fitment 242. The
stem of the T-piece 356 is connected to a pressure-tight
liquid varnish container 360. The level of liquid in the
container is indicated at 362 and it will be noted that
the pressure connection from the T-piece 356 is coupled
to the container above the level of the liquid. Container
360 has an outlet 364 at its lower end which is coupled
to a liquid varnish supply line 366 having said union 340
at its outer end. It will be appreciated that the air
pressure in line 348 pressurizes the air above the liquid
- 28 -
1071856
in container 360 and causes the liquid to be delivered under
pressure along line 366 to the spray gun. The air pres-
sure regulator 352 is controlled so that the pressure in
; each of the lines 358 and 366 is in the region of 40 p.s.i.
The application of decorative facings is
effected by simultaneously spraying sand of the'required
- colour and varnish onto the surface to be coated. Con-
` - ventional spray application techniques are employed in
manipulating the gun to produce the required effect.
Stencilling, masking and the like expedients may be em-
ployed where necessary.
The spray gun of Figs. 4 and 5 has a significant
advantage over conventional multiple nozzle spray gunsin
that at least partial atomization of the liquid belng
sprayed takes place inside the spray gun. This avoidsor
minimizes production of "fog" when spraying. In many
conventional spray guns, atomization does not occur until
the liquid leaves the spray nozzle with the result that
a substantial amount of "fog" is produced and significant
quantities of liquid are lost as a consequence.
A further advantage of the spray gun is that
i because the liquid spray issues in an annular stream
around the central sand stream, the-stream of sand is
enclosed by the liquid stream, which helps to constrain
the sand and which also ensures that the sand particles
are well coated with varnish by the time they reach the
surface to which the sand is being applied.
It will be appreciated that the spray gun may
be used not only in the application of decorative sur-
face coatings as described in the present application butalso in many other fields. For example, as a result of
;
- 29 _
10~1856
the facility which the gun has for spraying sand or liquid
alone, the gun may also be used for normal spraying
operations with paint, varnish and the like and also for
spraying particulate materials, e.g. in sand blasting
operations.
It is of course to be understood that the pre- -
ceding description applies to specific embodiments and
that many modifications are possible within the broad
scope of the invention. In particular, it is to be
understood that the process of the invention may be per-
- formed in the dyeing installations other than the specific
one shown in the drawings. For example, rotary ovens
could be used instead of the ovens shown in the drawings.
The form of the washing and dyeing tank may also vary.
Propeller type mixers may be used in place of or in addition
to the screw type mixer shown. With reference to the
binding material, although a number of examples have
been mentioned above, it is to be understood that they are
not exhaustive. For outdoor applications the binding mat-
erial should enclose the sand particles to protect againstcolour deterioration due to the effects of the weather.
- 30 -
