Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to the pneumatic gunning of plastic
refractory materials. In particular this invention relates to
improvements in a pneumatic gunning assembly for the gunning of
granulated plastic refractory material.
ire Art
The pneumatic gunning of granulated plastic refractory
material is an efficient method of forming a refractory lining on the
walls of a furnace or the like. The lining can be applied by a
pneumatic gunning process in a much shorter time period than that
required for other methods of forming a refractory lining.
One of the drawbacks of the pneumatic gunning process is,
however, that a substantial proportion of the granular particles of
refractory material which are sprayed onto the wall will rebound from
the wall and will not adhere to the wall. It is generally accepted
that the amount of plastic refractory material which will rebound in
this manner is about 20% of the total weight of refractory material
which is gunned. The efficiency of the gunning process has, however,
been such that this loss has been more than compensated for by the
labor saving of the gunning process,
I have found that the losses due to rebound can be overcome
by regranulating the rebound and blending the rebound with freshly
granulated refractory plastic material. This serves to substantially
reduce the losses due to rebound.
A further problem which has been experienced in attempting to
pneumatically gun granulated plastic refractory material is that of
preventing the granulated material reforming into large clumps after
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it has been granulated and before it is gunned. I have found that
this problem can be substantially eliminated by arranging the outlet
of the granulator so that it is directly above the inlet of the
pneumatic gunning device.
Summary of Invention
According to one aspect of the present invention, there is
provided in a pneumatic gunning mechanism for gunning granulated
refractory material having a granulator which has an input for
receiving plastic refractory and an output for discharging granulated
plastic refractory into a pneumatic gun, the improvement of a feeding
hopper having first and second feeding passages opening there through
which each communicate with the input of said granulator, said first
feeding passage being proportioned to permit a slab of plastic
refractory material to pass there through, said second feeding passage
serving to permit lumps of plastic refractory material to be admitted
to the granulator simultaneously with the slab of plastic material so
as to be mixed one with the other in the granulator.
According to another aspect of the present invention, there
is provided a pneumatic gunning assembly for gunning granulated
plastic refractory comprising a feeding hopper having at least one
feeding passage, a granulator having a granulator chamber which has an
inlet and an outlet a granulator mechanism mounted in said granulator
chamber, the output end of each through passage of the feeding hopper
communicating with the inlet of the granulated chamber, a pneumatic
gun having an input for receiving granulated plastic refractory
material and a discharge for discharging airborne particles of
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granulated plastic material, said pneumatic gun being located below
said granulator with the input of the pneumatic gun disposed directly
below the outlet of the granulator so that granulated particles of
refractory material which are discharged from the granulator fall
directly into the pneumatic gun in a loose granular form and are
pneumatically discharged therefrom before they have an opportunity to
reform into a large mass of plastic material.
The invention will be more clearly understood after reference
to the following detailed specification read in conjunction with the
drawings wherein:
Figure l is a pictorial front view of a pneumatic gunning
mechanism constructed in accordance with an embodiment of the present
invention;
Figure 2 is a diagram illustrating the various conduits of
the pneumatic gun;
Figure 3 is a partially sectioned pictorial view of the
feeding hopper and granulator and the input to the pneumatic gun;
Figure 4 is a sectional side view taken along the line 4-4 of
Figure 3;
Figure 5 is a partially sectioned pictorial view of a
pneumatic gun constructed in accordance with an embodiment of the
present invention; and
Figure 6 is a sectional side view taken along the line 6-6 of
Figure 5.
With reference to Figure 1 of the drawings, the reference
numeral 10 refers generally to a pneumatic gunning mechanism
constructed in accordance with an embodiment of the present invention.
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The mechanism 10 comprises a frame 12 which is mounted on a
wheeled platform 14. A pneumatic gun 16 is mounted on the platform 14
and a granulator 18 is mounted on beams 20 so as to be disposed
directly above the pneumatic gun 16. A feeding hopper 22 is mounted
directly above the granulator 18. The granulator 18 is powered by an
electric motor 24 which has a speed control handle 26 which may be
adjusted to control the output speed from the motor. The granulator
18 is driven through a gearbox 28 in a conventional manner.
Air is applied under pressure to the pneumatic gun 16 through
a conduit 30 which is adapted to releasable connected to a conduit 32
(~ig.2). The conduit 32 communicates with an air filter 34 which has
an output which is connected to an emergency shut-off valve 36. The
shut-off valve 36 is connected by conduits 38 and 40 to a T-joint 42.
A branch line conduit 44 extends from one end of the T-joint 42 and is
connected to a shut-off valve 46 which may be used to provide a
connection for secondary air supply such as a cleaning hose or the
like. The other branch of the T-joint 42 is connected to a pressure
control valve 48 which is connected to a second shut-off valve 50. A
pressure gauge 52 is connected to the shut-off valve 50 and a conduit
54 is connected to the pressure gauge 52. The conduit 54 is connected
to the input line 56 of the pneumatic gun 16.
With reference to Figures 3 and 4 of the drawings, it will be
seen that the feeding hopper 22 has a first feeding passage 58 and a
second feeding passage 60, each of which open there through. The first
feeding passage 58 has an input end 62 and an output end 64 and the
second feeding passage 60 has an input end 66 and an output end 68.
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The first feeding passage 62 is proportioned to receive a
slab or block of plastic refractory material 70 so as to permit it to
pass directly there through. Plastic refractory material is generally
packaged in slabs or blocks weighing 2 kg., and measuring
approximately 9 X 6 X 9 inches to 9 X 6 X 13 inches and the first
feeding passage 58 is proportioned to receive these slabs or blocks in
a free-fitting relationship which will permit the blocks to pass
there through under their own weight so that it is merely necessary to
load successive blocks into the first passage to ensure that it will
pass there through.
The second through passage 60 has a screen 72 located at its
input end 66. The screen 72 has openings 74 formed therein which are
proportioned to permit rebound particles of granular plastic
refractory material to pass there through which are of a size of
substantially equal to that of the granulated material at the output
of the granulator. Preferably the passages which are formed in the
screen 72 measure no more than 7/8" in diameter.
The second feeding passage 60 has an outer side wall 76 which
is angularly inclined downwardly and inwardly toward the divider wall
78. An inner side wall 80 cooperates with a flange 82 to form a
narrow passage 84. A metering device generally identified by the
reference numeral 86 is mounted for rotation directly below the narrow
passage 84. The metering device 86 comprises a rotor 88 which has a
central shaft 90 from which a plurality of blades 92 radiate, Discs
94 are located at opposite ends of the shaft 90. Pockets 96 are
located between the blades 92 and by rotating the rotor 88 about the
shaft 90, successive pockets 96 are exposed to the material passing
through the second feeding passage 60. A sprocket 98 (Fugue) is
mounted on the end of the shaft 90 and is connected by means of a
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chain 100 to a sprocket 102. The sprocket 102 is mounted on the shaft
104 of the granulator 18,
The shaft 104 and a second shaft 106 extend transversely of
the granulator 18 and have granulator blades 108 mounted thereon.
Fingers 110 are mounted on opposite sides of the granulator 18 and I
project between adjacent blades 108. The shaft 104 is driven by the
motor 24 (Foggily) through the gearbox 28. Rotation of the shaft 104
causes rotation of the shaft 90 and therefore rotation of the metering
device 86 to admit the rebound granular particles to the granulator
chamber 112. As illustrated in Figure 4 of the drawings, the
granulator chamber 112 has an inlet 114 and an outlet 116. The outlet
116 of the granulator 18 is disposed directly above the input shut
118 of the gun 16.
As shown in Figure 5 of the drawings, the shut 118
communicates with the input passage 120 of the pneumatic gun 16. The
pneumatic gun 16 is of a substantially conventional construction and
includes a rotor 122 Wheaties driven by a motor 124 through a gearbox
126. The rotor 122 has a plurality of pockets 128 formed therein. A
deflector blade 130 is located above a portion of the arc of travel of
the rotor immediately ahead of the gunning station which is generally
identified by the reference numeral 132. In the gunning station 132,
the air input line 56 is arranged to be aligned with one edge of
successive pockets 128 and a discharge conduit 134 it located at the
opposite edge of the pocket 128. Thus, air which is admitted to the
pocket 128 through the input line 56 will drive the granular particles
136 outwardly through the discharge conduit 134 and these particles
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will remain separated from one another by being suspended in the air
current. The particles 136 can then be gunned directly onto the
surface which is to be lined,
As indicated in Figure 5 of the drawings, the gun 16
preferably comprises a carriage 138 which is supported by wheels 140
and a front leg 142.
In use, the pneumatic gun 16 is located as shown in Figures 1
and 3 of the drawings with the input shut 118 located directly below
the outlet 116 of the granulator so that the granular particles will
fall directly from the outlet of the granulator into the input passage
120 of the gun. The rotor 122 is driven continuously during the
gunning operation so that as the granular material enters the pockets
128, successive pockets 128 are displaced into the gunning station 132
at which point the granular material is blown out of the pockets 128
and discharged through the discharge conduit 134.
Rebound granular particles which accumulate on the floor of
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the work site can be shoveled into the inlet end of the second
feeding passage 60 so as to be sorted by the screen 72 so that the
smaller particles are aloud to pass through the second feeding passage
60 to the metering device and are then metered as previously described
into the granulating chamber. The slabs or blocks 70 are fed to the
granulator through the first feeding passage and are granulated in a
conventional manner by the operation of the blades 108. When a
substantial amount of oversize rebound particles are accumulated on
the screen 72, these oversized particles can be loaded into the
granulator between successive slabs passing through the first feeding
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DS5-1503-37
passage 58 and will as a result, be subjected to a further granulating
step to reduce them to the required size.
It it essential to ensure that the refractory material is not
allowed to reclump into large particles after it is granulated and I
avoid this difficulty by ensuring that the granulated material is
discharged directly into the gunning machine in which it is collected
in small pockets in quantities which are so small that they are not
lively to reform under their own weight into a large clump.
Furthermore, the small pockets serve to ensure that even if the
granulated particles are placed in contact with lone another, they will
be dispersed when they are contacted by the high pressure air in the
gunning station 132.
It will also be apparent that by providing first and second
feeding passages, I have made it possible to utilize the rebound
granules which are not of an excessive size without subjecting these
granules to a regranulating step. Because the rebound material tends
to have a somewhat different moisture content than the originally
granulated material, I prefer to blend the rebound material with the
freshly granulated material and this is achieved by ensuring that both
the first and the second feeding passage open into the granulating
chamber of the granulator. If I were to merely feed blocks of fresh
plastic material followed by a load of rebound through the first
feeding passage 21l I would generate a stream of granulated material
at the gun output which would vary in characteristics according to
whether or not the material which was being gunned was predominantly
original gunning material or rebound gunning material.
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From the foregoing, it will be apparent that the present
invention provide a simple and efficient pneumatic gunning mechanism
which permits the gunning of rebound material and which permits the
gunning of granulated plastic refractory material.
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