Title: Portable concrete plant
Abstract: A portable concrete plant for producing ready mix concrete proximate to a location where the ready mix concrete is used. The portable concrete plant includes storage regions for storing components used in the ready mix concrete. The portable concrete plant also includes a slurry mixer for preparing slurry that is used in the ready mix concrete. The portable concrete plant further includes conveying systems for conveying the components from the storage regions and from the slurry mixer to a system discharge port.
Patent Number: 6,991,361 Issued on 01/31/2006 to Flood
| Inventors:
|
Flood; Jeffrey (Shakopee, MN)
|
| Assignee:
|
Advanced Concrete Innovations, Inc. (Jordan, MN)
|
| Appl. No.:
|
103649 |
| Filed:
|
March 21, 2002 |
| Current U.S. Class: |
366/18; 366/22; 366/27; 366/65; 366/67 |
| Current Intern'l Class: |
B28C 5/16 (20060101) |
| Field of Search: |
366/7,8,16,18,20,22,23,27,29,64-67,141,148,153.3,304,309
|
References Cited [Referenced By]
U.S. Patent Documents
| 1923151 | Aug., 1933 | Koehring.
| |
| 2015488 | Sep., 1935 | Manabe.
| |
| 4106111 | Aug., 1978 | Rose.
| |
| 4298288 | Nov., 1981 | Weisbrod.
| |
| 4452535 | Jun., 1984 | Reid.
| |
| 4588299 | May., 1986 | Brown et al.
| |
| 4589454 | May., 1986 | Kelley.
| |
| 4775275 | Oct., 1988 | Perry.
| |
| 4865457 | Sep., 1989 | Strehlow.
| |
| 4963031 | Oct., 1990 | Brown.
| |
| 4976378 | Dec., 1990 | Bush.
| |
| 5121989 | Jun., 1992 | Horton et al.
| |
| 5407299 | Apr., 1995 | Sutton.
| |
| 5427448 | Jun., 1995 | Macaulay et al.
| |
| 5718508 | Feb., 1998 | Williams.
| |
| 5730523 | Mar., 1998 | Flood.
| |
| 5908240 | Jun., 1999 | Hood.
| |
| 5934801 | Aug., 1999 | List et al.
| |
| 6030112 | Feb., 2000 | Milek.
| |
| 6126307 | Oct., 2000 | Black et al.
| |
| 6186654 | Feb., 2001 | Gunteret, Jr. et al.
| |
Other References
ALSLUR Brochure 1999.
|
Primary Examiner: Sorkin; David
Attorney, Agent or Firm: Helget; Gerald E., Briggs and Morgan, P.A.
Parent Case Text
RELATED U.S. APPLICATION DATA
This application is a continuation-in-part of U.S. application Ser. No. 09/826,979,
filed Apr. 5, 2001, which claims priority to U.S. Provisional Application Ser.
No. 60/194,703, filed Apr. 5, 2000.
Claims
What claimed is:
1. A portable concrete plant for preparing ready mix concrete, the portable concrete
plant comprising:
a frame having at least one set of wheels attached thereto for supporting the
frame above a ground surface and permitting the frame to be moved along the ground surface;
a cement storage region attached to the frame, wherein the cement storage region
stores cement, and wherein the cement storage region has a cement entry port and
a cement exit port;
a sand storage region attached to the frame, wherein the sand storage region
stores sand, and wherein the sand storage region has a sand entry port and a sand
exit port;
a rock storage region attached to the frame, wherein the rock storage region
stores rock, and wherein the rock storage region has a rock entry port and a rock
exit port;
a water storage region attached to the frame, wherein the water storage region
stores water, and wherein the water storage region has a water entry port and a
water exit port;
a slurry mixer attached to the frame, wherein slurry mixer has a slurry mixer
entry port and a slurry mixer exit port, wherein the cement exit port and the water
exit port are operably connected to the slurry mixer entry port, wherein the slurry
mixer prepares a slurry from cement and water; and wherein the slurry mixer exit
port is proximate a system exit port;
a conveyor system attached to the frame, wherein the conveyor system receives
rock from rock exit port and sand from the sand exit port and transports the rock
and sand to the system exit port; and further comprising a mixing apparatus mounted
on the frame proximate the system exit port for mixing the rock, sand and slurry
wherein the mixing apparatus imparts a swirling motion to the rock, sand and slurry
as the rock, sand and slurry pass through the mixing apparatus.
2. The portable concrete plant of claim 1, wherein the slurry mixer is attached
to the frame with a slurry mixer support frame, wherein the slurry mixer support
frame has a stationary portion and a pivoting portion, wherein the stationary portion
is attached to the frame, wherein the slurry mixer is attached to the pivoting
portion, and wherein the pivoting portion is pivotally attached to the stationary
portion so as to enable the slurry mixer to pivot between a transport position
and an extended position.
3. The portable concrete plant of claim 2, wherein the portable concrete plant
has a height of less than about 14 feet, when the slurry mixer is in the transport
configuration, and wherein the system exit port is positioned at a height of at
least 10 feet when the slurry mixer is in the extended position.
4. The portable concrete plant of claim 2, wherein the conveyor system pivots
between the extended position and the transport position as the slurry mixer is
pivoted between the extended position and the transport position.
5. The portable concrete plant of claim 1, and further comprising:
a cement weight monitoring mechanism operable attaching the cement storage region
to the frame; and
a sand weight monitoring mechanism operable attaching the sand storage region
to the frame;
a rock weight monitoring mechanism operable attaching the rock storage region
to the frame;
a water weight monitoring mechanism operable attaching the water storage region
to the frame.
6. The portable concrete plant of claim 1, wherein the slurry mixer comprises:
an outer enclosure;
a first stirring apparatus fixedly mounted to the outer enclosure; and
a second stirring apparatus rotatably mounted in the outer enclosure.
7. The portable concrete plant of claim 1, wherein the cement storage region,
the sand storage region, the rock storage region, and the water storage region
each include a load cell for continuously measuring the weight of components therein.
8. The portable concrete plant of claim 1, and further comprising an internal
combustion engine attached to the frame for powering the operation of the portable
concrete plant.
9. The portable concrete plant of claim 1, and further comprising a heat exchanging
apparatus attached to the frame, wherein the heat exchanging apparatus heats water
being delivered to the water storage region and cools hydraulic oil used to operate
the components in the portable concrete plant.
10. The portable concrete plant of claim 1, and further comprising a control
room attached to the frame, wherein the control room includes controls for controlling
the operation of the portable concrete plant.
11. A system for preparing ready mix concrete, the system comprising:
a portable concrete plant comprising:
a frame having at least one set of wheels attached thereto for supporting the
frame above a ground surface and permitting the frame to be moved along the ground surface;
a cement storage region attached to the frame, wherein the cement storage region
has a cement entry port and a cement exit port;
a sand storage region attached to the frame, wherein the sand storage region
has a sand entry port and a sand exit port;
a rock storage region attached to the frame, wherein the rock storage region
has a rock entry port and a rock exit port;
a water storage region attached to the frame, wherein the water storage region
has a water entry port and a water exit port;
a slurry mixer attached to the frame, wherein slurry mixer has a slurry mixer
entry port and a slurry mixer exit port, wherein the cement exit port and the water
exit port are operably connected to the slurry mixer entry port, wherein the slurry
mixer prepares a slurry from cement and water, and wherein the slurry mixer exit
port is located proximate a system exit port;
a conveyor system attached to the frame, wherein the conveyor system receives
rock from rock exit port and sand from the sand exit port and transports the rock
and sand to a the system exit port,
and wherein the slurry mixer comprises:
an outer enclosure;
a first stirring apparatus fixedly mounted to the outer enclosure; and
a second stirring apparatus rotatably mounted in the outer enclosure.
12. The system of claim 11, wherein the slurry mixer is attached to the frame
with a slurry mixer support frame, wherein the slurry mixer support frame has a
stationary portion and a pivoting portion, wherein the stationary portion is attached
to the frame, wherein the slurry mixer is attached to the pivoting portion, and
wherein the pivoting portion is pivotally attached to the stationary portion so
as to enable the slurry mixer to pivot between a transport position and an extended position.
13. The system of claim 12, wherein the portable concrete plant has a height
of less than about 14 feet, when the slurry mixer is in the transport configuration,
and wherein the system exit port is positioned at a height of at least 10 feet
when the slurry mixer is in the extended position.
14. The system of claim 12, wherein the conveyor system pivots between the extended
position and the transport position as the slurry mixer is pivoted between the
extended position and the transport position.
15. The system of claim 11, and further comprising:
a cement weight monitoring mechanism operably attaching the cement storage region
to the frame; and
a sand weight monitoring mechanism operable attaching the sand storage region
to the frame;
a rock weight monitoring mechanism operable attaching the rock storage region
to the frame; and
a water weight monitoring mechanism operable attaching the water storage region
to the frame.
16. The system of claim 11, where in the slurry mixer has a self-cleaning configuration
in which the first stirring apparatus and the second stirring apparatus clean each
other and the second stirring apparatus cleans an inner surface of the outer enclosure
as the second stirring apparatus is rotated in the outer enclosure.
17. The system of claim 11, and further comprising a mixing apparatus mounted
on the frame proximate the system exit port for mixing the rock, sand and slurry.
18. They system of claim 17, wherein the mixing apparatus imparts a swirling
motion to the rock, sand and slurry as the rock, sand and slurry pass through the
mixing apparatus.
Description
FIELD OF THE INVENTION
The present invention relates generally to a concrete plant. More particularly,
the present invention relates to a portable concrete plant.
BACKGROUND OF THE INVENTION
Concrete is used in constructing a variety of different structures such
as buildings, bridges and roads. Typically concrete is prepared in the form of
ready mix concrete at a central location and then transported via truck to a location
where the ready mix concrete is to be used. While this technique allows larger
batches of ready mix concrete to be produced, the quality of concrete varies significantly
depending on the distance between location where the ready mix concrete is prepared
and the location where the ready mix concrete is used as the ready mix concrete
begins the curing process as soon as it is prepared. As such, it is often necessary
to add components to the ready mix concrete that either slows or speeds the curing process.
In an attempt to overcome the drawbacks associated with producing ready mix concrete
at a central location and then trucking the ready mix concrete to the use locations,
it has been proposed to create a concrete plant that is portable such that the
portable concrete plant may be transported to a location that is proximate where
the ready mix concrete will be used. For example, Flood, U.S. Pat. No. 5,730,523,
describes a portable concrete plant that is mounted on a single vehicle. The Flood
portable concrete plant includes hoppers for storing rock, sand, cement and water.
The Flood portable concrete plant also has a conveyor system that conveys the rock,
sand and cement into a rotating drum where the components are mixed with water
to prepare ready mix concrete. A pump is used for dispensing the ready mix concrete
from the rotating drum.
Weisbrod, U.S. Pat. No. 4,298,288, discloses a portable concrete apparatus
that is suited for preparing ready mix concrete proximate to a location where the
concrete is to be used. The Weisbrod apparatus feeds rock, sand, cement and water
at different locations along a mixing auger. Once sufficiently mixed, the ready
mix concrete is pumped through a hose to the location where it is used. The Weisbrod
system is particularly suited for use with preparing relatively small amounts of
ready mix concrete.
One of the important components of a system that prepares ready mix concrete
is the slurry mixer that mixes water, cement and other components into a slurry,
which then can be mixed with rock and sand to produce the ready mix concrete. Brown
et al., U.S. Pat. No. 4,588,299, and Strehlow, U.S. Pat. No. 4,865,457, each disclose
a slurry mixer having a horizontally oriented mixing region.
Milek, U.S. Pat. No. 6,030,112, discloses a slurry batch mixer that has an
elongated configuration. The slurry batch mixer has a trough with a curved bottom.
A ribbon type screw conveyor is mounted in the trough parallel to an axis of the
trough. Rotation of the screw conveyor not only mixes the components together but
also conveys the mixed components to a discharge port of the trough. Williams,
U.S. Pat. No. 5,718,508, discloses a self-cleaning slurry mixer having a cylindrical
shape with a feed screw extending therethrough to mix together the components and
to convey the mixed slurry to the slurry outlet. Macauley et al., U.S. Pat. No.
5,427,448, describes a twin screw slurry mixer where the screws are oriented parallel
to each other.
Hood, U.S. Pat. No. 5,908,240, describes a tank-type slurry mixer that has
two sets of paddles rotatably mounted therein. The paddles cause the mixture to
be drawn in the downward direction and then flow upwardly along the side walls
of the tank. Brown, U.S. Pat. No. 4,963,031, also discloses a tank-type slurry
mixer. None of the prior art references or discloses a portable concrete plant
that is suitable for producing ready mix concrete at rates of between 75 and 200
cubic yards per hour as is typically required for commercial applications.
Accurately controlling the flow of rock and sand also plays an important
role in preparing ready mix concrete with consistent characteristics. Bush, U.S.
Pat. No. 4,976,378, describes a paddle-type feed metering system. The Bush device
includes four paddles that are rotatably mounted in an enclosure. Rotation of the
paddle dispenses a predetermined weight of material.
SUMMARY OF THE INVENTION
The present invention relates to a portable concrete plant for preparing ready
mix concrete proximate to a location where the ready mix concrete is to be used.
The portable concrete plant includes a frame, a rock storage region, a sand storage
region, a cement storage region, a water storage region, a slurry mixer, and a
conveyor system.
The frame has at least one set of wheels attached thereto for supporting the
frame above a ground surface and permitting the frame to be moved along the ground
surface. The cement storage region stores cement and is attached to the frame.
The cement storage region has a cement entry port and a cement exit port. The sand
storage region stores sand and is attached to the frame. The sand storage region
has a sand entry port and a sand exit port. The rock storage region stores rock
and is attached to the frame. The rock storage region has a rock entry port and
a rock exit port. The water storage region stores water and is attached to the
frame. The water storage region has a water entry port and a water exit port.
The slurry mixer is attached to the frame. The slurry mixer has a slurry mixer
entry port and a slurry mixer exit port. The cement exit port and the water exit
port are operably connected to the slurry mixer entry port. The slurry mixer prepares
a slurry from cement and water.
The first conveyor system is attached to the frame. The first conveyor system
receives rock from the rock exit port and sand from the sand exit port and transports
the rock and sand to a system exit port. The first conveyor system and the slurry
mixer exit port intersect proximate to the system exit port to cause the slurry
to be mixed with the sand and rock for preparing the ready mix concrete.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a portable concrete plant according to the present
invention in a use configuration.
FIG. 2 is a side view of the portable concrete plant in a transport configuration.
FIG. 3 is a top view of the portable concrete plant and material feed conveyor systems.
FIG. 4 is a side view of a cement storage region of the portable concrete plant.
FIG. 5 is a side view of a sand flow metering device for use in the portable
concrete plant.
FIG. 6 is a sectional view of the sand flow metering device taken along a line
6—6 in FIG. 5.
FIG. 7 is a sectional view of the slurry mixer taken along a line 7—7
in FIG. 1.
FIG. 8 is a sectional view of the slurry mixer taken along a line 8—8
in FIG. 7.
FIG. 9 is a back view of the portable concrete plant.
FIG. 10 is a sectional view of a concrete discharge device for the portable
concrete plant.
FIG. 11 is a schematic illustration showing material flow paths into and out
of the slurry mixer.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to a portable concrete plant, as most clearly
illustrated at
10 in FIGS. 1 and 2. The portable concrete plant
10
is capable of producing between about 75 and 200 cubic yards of ready mix concrete
per hour. The portable concrete plant
10 is suited for use proximate a location
where the ready mix concrete is to be used. The portable concrete plant
10
thereby reduces the cost of transporting the ready mix concrete to the location
where the concrete is to be used.
The portable concrete plant
10 also enhances the quality of the concrete
by eliminating wet or dry loads that are caused by variations in delivery time
to the location where the ready mix concrete is to be used. By reducing these variations,
qualities of the finished concrete such as strength are enhanced.
It is possible to use the portable concrete plant
10 in a variety of locations
with only minimal preparations to the locations, such as providing a relatively
flat and stable surface. The portable concrete plant
10 has a relatively
low center of gravity, which makes the portable concrete plant
10 stable
to use on a variety of ground surfaces.
The portable concrete plant
10 generally includes a frame
20, a
material storage region
22, a material mixing region
24 and a mixed
material delivery region
26 that are each mounted to the frame
20.
The frame
20 is preferably fabricated to extend around the components of
the portable concrete plant
10.
The frame
20 is constructed to maintain the components of the portable
concrete plant
10 in a fixed position not only during use of the portable
concrete plant
10 but also during transportation of the portable concrete
plant
10 to a location where the portable concrete plant
10 is to
be used.
The frame
20 is preferably selected with a width, length and height that
permit the portable concrete plant
10 to meet substantially all of the applicable
road size regulations such that the portable concrete plant
10 may be transported
over a significant percentage of the roads without obtaining special permits. For
most applications, the width is less than about 102 inches, the length is less
than about 61 feet, and the height is less than about 13 feet 6 inches.
The frame
20 preferably includes a gooseneck
18 that facilitates
attaching the portable concrete plant
10 to a truck for transporting the
portable concrete plant
10 to a desired use location.
The frame
20 is supported by at least one set of wheels
21 that
permit the portable concrete plant
10 to be easily transported to a desired
use location. The number of sets of wheels
21 and the number of wheels in
each set of wheels
21 is selected based upon the applicable weight limitations.
For most applications, the portable concrete plant
10 has two sets of wheels
21 that include two wheels on each side of the frame
20.
Sides of the portable concrete plant
10 are preferably covered by tarps
(not shown) that protect the components of the portable concrete plant
10
during cold weather operations and facilitate heating of the components to prevent
freezing of the materials in the portable concrete plant. The tarps also protect
the portable concrete plant
10 during transportation or while not in use.
A heat exchanger (not shown) may be positioned underneath the tarp to heat the
materials used in the portable concrete plant
10 during cold weather to
prevent freezing of materials used in the portable concrete plant
10.
The tarps are preferably retractable to a relatively small region proximate the
top of the frame when the tarps are not in use to provide access to the components
of the portable concrete plant
10. A person of ordinary skill in the art
will appreciate that a variety of materials are suitable for use in fabricating
the tarp. A person of ordinary skill in the art will also appreciate that a variety
of mechanisms are suitable for either automatically or manually moving the tarps
from an extended position to the retracted position.
The material storage region
22 preferably has a separate storage area
for each of the materials that are used for preparing the ready mix concrete, as
most clearly illustrated in FIGS. 1 and 3. The material storage region
22
preferably includes a portland cement storage region
30, a sand storage
region
32, a rock storage region
34, and a water storage region
36.
The material storage region
22 may also include storage regions for one
or more admixes that are added during the concrete preparation process.
While the present invention only illustrates the use of two rock storage regions
34, a person of ordinary skill in the art will appreciate that it is possible
to utilize the concepts of the present invention in conjunction with multiple sizes
of rock that are each stored separately.
The cement storage region
30 includes a cement hopper
40 with a
substantially enclosed upper end and a tapered lower portion
42. The cement
hopper
40 has a capacity of greater than 50 cubic feet, preferably between
100 cubic feet and 200 cubic feet and most preferably about 150 cubic feet.
Proximate the lower portion
42, the cement storage region
30
has a flow control mechanism
44 that controls the flow of cement from the
cement storage region
30, most clearly illustrated in FIG. 4.
Preferably, the cement storage region
30 includes two flow control
mechanisms
44. Using the two flow control mechanisms
44 enhances
the ability to accurately control the rate at which cement is dispensed from the
cement hopper
40. Using two flow control mechanisms
44 also enhances
the even loading of a paddle system in the slurry mixer
120 and thereby
reduces large torque differentials that can lead to potential damage of the components
in the slurry mixer
120. Using the two flow control mechanisms
44
also enhances the ability to rapidly load the cement into the slurry mixer
120.
In particular, approximately 5,640 pounds of cement, which is needed for preparing
10 yards of ready mix concrete in a 6 bag mix protocol, is loaded into the slurry
mixer
120 in less than 30 seconds and preferably about 15 seconds.
The flow control mechanism
44 preferably includes a rotatably mounted
gate valve. However, a person of ordinary skill in the art will appreciate that
other valve mechanisms may be used to control the flow of cement from the cement
hopper
40. Operation of the flow control mechanism
44 is preferably
controlled by operable attachment to a hydraulic system in the portable concrete
plant
10, which is described in more detail herein. Alternatively, it is
possible to control the operation of the flow control mechanism using an electrical
or pneumatic control system.
The cement hopper
40 is preferably mounted to the frame
20 using
a load cell
46 that permits the weight of cement hopper
40 to be
monitored on a continuous basis. Continuous monitoring of the weight of the cement
hopper
40 enhances the ability to accurately add cement during the concrete
preparation process. Such a system is typically referred to as a loss in weight
charge system.
To enhance the ability to produce a steady flow of cement from the cement hopper
40, the cement storage region
30 preferably includes a vibrator
48
operably attached thereto. To minimize the noise associated with the bin vibrator
48 as well as the wear and tear on the components of the cement storage
region
30, the bin vibrator
48 is preferably only activated while
the flow control mechanism
44 is in operation.
A dust collection system
50 is preferably provided on the cement storage
region
30 to collect dust that is generated by moving the cement into and
out of the cement storage region
30. The dust collection system
50
includes a series of filter cartridges (not shown) on which the dust is collected.
The total surface area provided by the filter cartridges is between 500 and 2000
square feet and preferably about 1000 square feet.
At selected intervals the dust is removed from the filter cartridges. Since the
filter cartridges are mounted above the cement storage region
30, the dust
falls into the cement storage region
30 when it is removed from the filter
cartridges. This recycling system minimizes the amount of cement dust that must
be disposed of and extends the life of the filter cartridges. The dust collection
system
50 also preferably includes a port (not shown) that provides operators
with the ability to inspect the filter cartridges to determine when it is necessary
to replace the filter cartridges. The port also provides the ability to easily
access the filter cartridges when it is necessary to replace the filter cartridges.
Cement is preferably supplied to the cement storage region
30 from
an auxiliary bulk cement storage tanker (not shown) that is operably connected
to the cement storage region
30 with a cement transfer line (not shown).
The auxiliary bulk cement storage tanker is operably connected to the portable
concrete plant
10 using hydraulically operated control valves that permit
the flow of cement to be controlled from a control room on the portable concrete
plant
10. Transfer of the cement from the auxiliary bulk cement storage
tanks is preferably performed using conventionally known techniques such as with
blowing air.
The sand storage region
32 includes a sand hopper
60 having a substantially
open upper portion
62 that tapers down to a lower portion
64. The
hopper
60 preferably has a storage capacity of approximately seven cubic
yards. The substantially open upper portion
62 permits sand to be replenished
into the sand hopper
60. Proximate the lower portion
64, the sand
storage region
32 has a flow control mechanism
66 that controls the
flow of sand from the sand storage region
32. The flow control mechanism
66 is preferably a paddle metering valve
68 such as is illustrated
in FIGS. 5 and 6. The paddle metering valve
68 reduces material bridging
in the sand hopper
60 and provides the ability to individually control the
rates at which the materials are dispensed from the sand hopper
60.
The paddle metering valve
68 generally includes two elements the rotatable
paddle element
70 and the gate element
72. The rotatable paddle element
70 has a plurality of paddles
74 extending therefrom. The rotatable
paddle element
74 is oriented to rotate parallel to the direction in which
the sand is falling out of the sand hopper
60.
The gate element
72 is pivotable between a closed position oriented adjacent
to the rotatable paddle element
70 and an open position. When in the closed
position the rotatable paddle element
70 and the gate element
72
substantially prevent flow of sand from the sand hopper
60. When the gate
element
72 pivots from the closed position to the open position as indicated
by arrow
76, the sand is permitted to flow from the sand hopper
60.
Rotation of the rotatable paddle element
70 thereby enhances the
ability to produce an even sand flow rate. Changing the rate at which the rotatable
paddle element
70 is rotated allows the sand flow rate to be changed. Positioning
the gate element
72 at intermediate positions between the open position
and the closed position also permits the sand flow rate to be varied.
The sand storage region
32 is preferably mounted to the frame
20
using a load cell
77 that permits the weight of sand hopper
60 to
be monitored on a continuous basis. Continuous monitoring of the weight of the
sand hopper
60 enhances the ability to accurately add sand during the concrete
preparation process. Continuous monitoring of the weight of sand in the sand hopper
60 also provides the operator with an indication as to when it is necessary
to replenish the sand in the sand hopper
60.
To enhance the ability to produce a steady flow of sand from the sand hopper
60,
the sand storage region
32 preferably includes a vibrator
78 operably
attached thereto. To minimize the noise associated with the bin vibrator
78
as well as the wear and tear on the components of the sand storage region
32,
the bin vibrator
78 is preferably only activated while the flow control
mechanism
66 is operating.
The rock storage region
34 includes a rock hopper
80 having a substantially
open upper portion
82 that tapers down to a lower portion
84, as
most clearly illustrated in FIG. 1. The hopper
80 preferably has a storage
capacity of approximately seven cubic yards. The substantially open upper portion
82 permits rock to be replenished into the rock hopper
80. Proximate
the lower portion
84, the rock storage region
34 has a flow control
mechanism
86 that controls the flow of rock from the rock storage region
34. The flow control mechanism
86 preferably includes a pair of gates
that are pivotally mounted proximate the lower portion
84.
Pivoting of the gates to a closed position prevents rock from flowing out
of the rock hopper
80. Pivoting of the gates to an open position permits
rock to flow out of the rock hopper
80. Pivoting of the gates between the
open position and the closed position is preferably controlled by a hydraulic cylinder
(not shown). The metering valve preferably includes a flow control that permits
slow opening of the valve to promote controlled free fall and rapid closing of
the valve to promote accurately attaining the target material weight.
The rock hopper
80 is mounted to the frame
20 using a load cell
90 that permits the weight of the rock hopper
80 to be obtained on
a continuous basis. Continuous monitoring of the weight of the rock hopper
80
enhances the ability to accurately add rock during the concrete preparation process.
Continuous monitoring of the weight of rock in the rock hopper
80 also provides
the operator with an indication as to when it is necessary to replenish the rock
in the rock hopper
80.
To enhance the ability to produce a steady flow of rock from the rock hopper
80,
the rock storage region
34 preferably includes a vibrator
92 operably
attached thereto. To minimize the noise associated with the bin vibrator
92
as well as the wear and tear on the components of the rock storage region
34,
the bin vibrator
92 is preferably only activated while the flow control
mechanism
86 is in operation.
The water storage region
36 includes a substantially enclosed vessel
110
having a capacity of between about 100 gallons and 500 gallons. The portable concrete
plant
10 has a weight cell
112 that attaches the water storage vessel
110. The weight cell
112 permits the weight of the water storage
vessel
110 to be continuously monitored to accurately control the delivery
of water in the cement preparation process. The weight cell
112 also provides
the operator with an indication when it is necessary to refill the water storage
vessel
110.
As an alternative to manually monitoring the water level in the water storage
vessel
110, the water level may be automatically controlled to refill the
water storage vessel
110 from a water source. Depending on the location
where the portable concrete plant
10 is used, the water source is typically
either a tanker filled with water or attachment to a municipal water supply such
as through a fire hydrant.
The material mixing region
24 includes a slurry mixer
120 having
a generally cylindrical shape with a side wall
122 and a base wall
124
that encloses a lower end of the slurry mixer
120, as most clearly illustrated
in FIGS. 7-9.
The slurry mixer
120 is pivotally mounted to the frame
20 so that
the slurry mixer
120 is movable between an extended position (illustrated
in FIG. 1) and a storage position (illustrated in FIG. 2). When in the storage
position, the portable concrete plant
10 has a height that permits the portable
concrete plant
10 to be transported over most roads. When in the extended
position, an exit port from the slurry mixer
120 is sufficiently high to
permit slurry to be delivered from the slurry mixer
120 to a conventional
concrete truck (not shown) by gravity. The portable concrete plant
10 thereby
obviates the need to pump slurry, which is often difficult because of the viscosity
of the slurry.
A slurry mixer support frame
212 has a stationary portion that extends
upwardly
from the frame
20 and a pivoting portion
216 opposite the frame
20.
Pivoting of the pivoting portion
216 with respect to the stationary portion
214 is preferably controlled with a hydraulic cylinder. Once in the extended
position, at least one locking pin (not shown) is extended through the pivoting
portion
216 and the stationary portion
214 to thereby lock the pivoting
portion
216 in the extended position without relying on the hydraulic system.
The locking pins are preferably moved between the locked and unlocked positions
using a hydraulic cylinder (not shown).
A dispensing channel
126 is provided in the base wall
124 for conveying
slurry out of the slurry mixer
120 as illustrated in FIGS. 7 and 8. A dispensing
auger
128 is rotatably mounted in the dispensing channel
126. Rotation
of the dispensing auger
128 conveys the slurry out of the dispensing channel
126. An end of the dispensing auger
128 is located proximate to the
discharge boot
150.
A slurry control valve
154 substantially covers the end of to dispensing
auger so that slurry only flows out of the slurry mixer
120 when desired.
The slurry control valve
154 is pivotable between an open position and a
closed position. Pivoting of this slurry control valve
154 between the open
position and the closed position is preferably controlled using a hydraulic cylinder
or other similar mechanism (not shown).
The slurry mixer
120 has a paddle system
130 rotatably mounted
therein for mixing together the materials placed in the slurry mixer
120.
Rotation of the paddle system
130 is preferably controlled by a top-mounted
motor
131. Using the top-mounted motor
131 eliminates the need to
use high maintenance shaft seals and permits the dispensing auger
128 to
span the entire bottom of the slurry mixer
120. This configuration also
enhances the ability to perform end of day cleaning on the components of the slurry
mixer
120.
The paddle system
130 has a preferably self-cleaning configuration to
facilitate removing all of the slurry from the slurry mixer
120 at the end
of each work day. The self cleaning capability thereby minimizes the time and effort
needed to clean the slurry mixer
120 and assures complete slurry removal
from the slurry mixer
120.
The paddle system
130 includes a central member
132 and lower rotating
member
134 that extends from the central member
132 to proximate
the side wall
122.
Lower mixing members
140 extend upwardly from the lower rotating member
134. An upper wiper
142 may be attached to an upper end of the lower
mixing members
140 so that the upper wipers
142 slide over a top
cover
145 to thereby wipe slurry mixture from the top cover
145.
Similarly, upper mixing members
146 extend downwardly from the top cover
145. A lower wiper
148 may be attached to a lower end of the upper
mixing member
146 so that the lower wiper
148 slides over an upper
surface of the lower member
134 to thereby wipe slurry mixture from the
lower member
134.
The upper mixing members
146 are preferably removably mounted in the slurry
mixer
24. This configuration permits the upper mixing members
146
to be removed when damaged or when otherwise desired. The upper mixing members
are preferably attached to the top cover
145 of the slurry mixer
24
using bolts (not shown).
Rotation of the lower rotating members
134 causes the lower mixing
members
140 to move between the upper mixing members
146 and thereby
cause the water, cement and other components placed in the slurry mixer
120
to be mixed together to produce a slurry. The slurry mixer
120 permits the
water, cement and other components to be mixed in less than 60 seconds and preferably
between about 15 seconds and 30 seconds. The slurry mixer
120 of the present
invention promotes a high degree of mixing such that nearly all of the cement particles
are coated with water.
While not necessary, the components in the slurry mixer
120 may be plastic
coated to reduce sticking of the slurry to the components of the slurry mixer
120.
Using plastic coated components in the slurry mixer
120 also reduces rotational
friction and lowers power consumption associated with operating the slurry mixer
120. Plastic coated components in the slurry mixer
120 also enhance
the ability to accurately transfer slurry from the slurry mixer
120. Additionally,
using plastic coated components in the slurry mixer
120 enhances the ability
to clean the slurry mixer
120 at the end of the day.
The upper mixing members
146 are offset from the lower mixing members
140, as most clearly illustrated in FIGS. 7 and 8, such that as the lower
rotating member
134 is rotated, the lower mixing members
140 pass
between the upper mixing members
146. The upper mixing members
146
and the lower mixing members
140 may be configured such that the upper mixing
members
146 and the lower mixing members
140 scrape against each
other to thereby reduce the accumulation of slurry on the upper mixing members
146 and the lower mixing members
140.
The outer most lower mixing member
140 preferably has a side wiper
147
that slides along the side wall
122 as the lower rotating member
134
is rotated to thereby reduce accumulation of slurry on the side wall
122.
A bottom wiper
151 is preferably attached to the lower member
134
so that the bottom wiper
151 slides along the bottom surface
124
of the slurry mixer to reduce accumulation of unmixed cement on the bottom surface
124.
The portable concrete plant
10 has the ability to use admixtures that
control and/or enhance characteristics of the ready mix concrete prepared by the
portable concrete plant
10. Examples of suitable admixtures are air entrainment
materials, conventional and non-corrosive accelerators, and plasticizers. Certain
of these admixtures may be added to the slurry mixer
120 while others may
be used at other locations such as on the dry material conveyor
190 or at
the discharge boot
150, as illustrated in FIG. 3.
The operation of the components of the portable concrete plant
10 is preferably
controlled with a hydraulic system. Using the hydraulic system is preferable because
hydraulic systems have the ability to produce high levels of forces in a relatively
safe and reliable manner. The hydraulic system also permits infinitely variable
control of the speed at which components such as the conveyor belt are operated.
A person of ordinary skill in the art will appreciate that it is possible to use
alternative mechanisms to control the operation of the components of the portable
concrete plant
10 using the concepts of the present invention.
The hydraulic system is preferably operated at a pressure of about 2,000 pounds
per square inch. Using this moderate pressure level enhances the safety of the
components when compared with high-pressure systems that operate at pressures of
5,000 pounds per square inch or more. This moderate pressure level also reduces
wear on the pumping head used to generate the pressure used in the hydraulic system.
Pumping heads used in conjunction with the hydraulic system preferably have a variable
flow configuration that permits the pumping heads to slow down when oil is not
needed. This feature also reduces wear on the components of the hydraulic system.
Each of the components that is operated by the hydraulic system preferably has
a partial by-pass configuration that permits the component to operate at a very
slow rate of rotation even when the component is not activated. By using the by-pass
circuit the large initial forces that are imparted when rotation is initially begun
are substantially reduced.
The hydraulic system is preferably powered by an internal combustion engine
162
that is mounted to the frame
20. Incorporating the internal combustion engine
162 into the portable concrete plant
10 allows the portable concrete
plant
10 to be operated without regard to the proximity of utility service
to the location where the portable concrete plant
10 is to be used. A preferred
internal combustion engine
162 for use with the portable concrete plant
10 is a diesel engine having a horsepower in that range of 150 to 300 and
preferably about 220. A particularly suited internal combustion engine
162
for use with the portable concrete plant
10 is manufactured by Caterpillar
Co. A person of ordinary skill in the art will appreciate that it is possible to
power the operation of the portable concrete plant
10 with a variety of
other techniques such as through electricity.
The internal combustion engine
162 may be removably mounted to the frame
10 on a skid (not shown) that permits the unit to be readily detached from
the portable concrete plant
10 for performing maintenance or repair of the
internal combustion engine
162.
To power the operation of the internal combustion engine
162, the portable
concrete plant
10 preferably includes an on-board fuel storage tank
164.
The on-board fuel storage tank
164 has a capacity of between about 50 gallons
and 200 gallons and preferably about 100 gallons.
Also operably attached to the internal combustion engine
162 is an air
compressor (not shown) to provide compressed air as needed for the operation of
certain components on the portable concrete plant
10. For example, the compressed
air may be used to convey the cement from the auxiliary bulk cement storage tanker
to the cement hopper
40.
The internal combustion engine
162 further preferably includes a high
output AC alternator (not shown) operably connected thereto to power the operations
of electrically powered components on the portable concrete plant
10. The
high output AC alternator facilitates the operation of the portable concrete plant
10 without regard to the availability of electrical power where it is desired
to use the portable concrete plant
10. For example, the alternator may be
used to provide power for a computer in the control room
170.
The portable concrete plant
10 preferably includes a heat exchanger
168
mounted thereto. The heat exchanger
168 cools hydraulic oil used in the
hydraulic system
160 while heating water that is used in preparing the slurry.
Heating the water is particularly useful when the portable concrete plant
10
is used in cold climates because the heated water reduces the need to add acceleration
or retardation admixtures during the concrete preparation process. Cooling the
hydraulic oil in the hydraulic system also increases the efficiency of the hydraulic system.
The portable concrete plant
10 preferably includes a control room
170.
The control room
170 provides continuous oversight of the conditions in
each of the components of the portable concrete plant
10. The control room
170 permits an operator to adjust nearly all parameters relating to the
operation of the portable concrete plant
10. The control room
170
is preferably substantially enclosed to protect the controls from damage by environmental
factors such as rain or corrosion by materials being processed in the portable
concrete plant
10.
The operation of the portable concrete plant
10 is preferably controlled
by at least one computer (not shown) located in the control room
170. The
computer preferably permits the individual components of the portable concrete
plant
10 to be simultaneously controlled. A person of ordinary skill in
the art will also appreciate that alternate methods are possible to control the
operation of the portable concrete plant
10.
The portable concrete plant
10 preferably includes levelers
180
that permit the portable concrete plant
10 to be maintained in a level orientation
regardless of the conditions at the location where the portable concrete plant
10 is to be used. The levelers
180 thereby obviate or substantially
reduce the need to excavate at the intended use site. Preferably there are a series
of six levelers
180 with the levelers being spaced around the frame
10.
The levelers
180 are extendable varying degrees from the frame
20
using an operable attachment to the hydraulic system. The levelers
180 preferably
have a range of motion of up to 24 inches. To further stabilize the portable concrete
plant
10, a plate (not shown) may be placed beneath one or more of the levelers
180.
Because of the height of the portable concrete plant
10 when the slurry
mixer
24 is in the extended position, a levelers
180 proximate the
back end of the portable concrete plant
10 are preferably mounted on outriggers
181. The outriggers
181 are pivotable between a retracted or transport
position (as illustrated in FIG. 2) and an extended position (as illustrated in
FIG. 9). Pivoting of the outriggers
181 between the extended and retracted
positions is preferably controlled by a hydraulic system.
The portable concrete plant
10 has a first conveyor
190 for transferring
the ready mix concrete components to the concrete mixing truck. The first conveyor
190 passes beneath the sand flow control mechanism
66 and the rock
flow control mechanism
86 to thereby receive sand and rocks from the sand
hopper
60 and the rock hopper
80, respectively. The first conveyor
190 conveys the sand and rock to a second conveyor
192. The speed
rate at which the first conveyor
190 operates is adjustable to permit precise
control of the rate at which sand and rock are delivered to the discharge boot
150.
The second conveyor
192 is preferably operably attached to the pivoting
section
216 so that as the pivoting section
216 is moved from the
storage position to the extended position, the second conveyor
192 is also
moved from a storage position to an extended position.
Proximate the intersection of the first conveyor
190 and the second
conveyor
192 is a protective cover (not shown) that extends over the first
conveyor
190 and the second conveyor
192 to prevent sand and stones
from falling off the first and second conveyors
190,
192. The protective
cover may also include a door (not shown) pivotally mounted proximate to an exit
thereof to further reduce the potential for sand and rock falling off the first
and second conveyors
190,
192. Additionally, the conveyor may include
side shields (not shown) that are positioned partially over the conveyors proximate
the intersection of the conveyor
190 and the second conveyors
192
to prevent sand and rock from falling off the conveyors.
The discharge boot
150 preferably extends from the back end of the portable
concrete plant
10, as most clearly illustrated in FIGS. 1 and 2. However,
a person of ordinary skill in the art will appreciate that the discharge boot
150
may also extend from the front end or sides of the portable concrete plant
10
using the concepts of the present invention.
The discharge boot
150 permits adjustment to compensate for different
concrete mixers so that charge height can be varied. Because of the position of
the concrete discharge boot
150, it is not necessary to excavate a loading
pit. It is also possible to pivotally attach an end of the second conveyor
192
that is attached to the discharge boot
150 so that a height of the second
conveyor
192 may be adjusted depending on the height of the concrete mixing trucks.
The discharge boot
150 receives rock and sand from the second conveyor
192 and slurry from the slurry mixer
24. The discharge boot
150
imparts a spiral motion to the slurry, rock and sand as these components are fed
into the drum of the concrete mixer truck, as most clearly illustrated in FIG.
10. In this technique the slurry is jacketed by the rock and sand to promote uniform
mixture of the slurry with the rock and sand. The spiral motion accelerates loading
of the sand, rock and slurry while preventing clogging of the discharge boot
150.
Using the spiral loading motion also improves the mix quality by blending the rock
and sand to prevent material segmentation. The spiral motion imparted by the discharge
boot
150 is preferably in the same direction as the spiral motion of the
drum on the concrete mixer truck.
The discharge boot
150 preferably has a sleeve
194 extending therefrom.
The position of the sleeve
194 with respect to the discharge boot
150
is adjustable such that the sleeve
194 can extend to proximate the concrete
mixer truck to minimize spills. Movement of the sleeve
194 with respect
to the discharge boot
150 is preferably controlled by a hydraulic cylinder
197.
To further reduce the amount of dust and other materials emitted from the portable
concrete plant
10, a drum sealing ring
193 extends from the sleeve
194. When the sleeve
194 is lowered into a feed funnel (not shown)
on the concrete mixer truck, the drum sealing ring
193 seats substantially
against an upper surface of the feed funnel.
Proximate the discharge boot
150, the portable concrete plant
10
may also include an admix feed chute (not shown). The admix feed chute enables
admix, such as an accelerator or reinforcing fibers to be added to the ready mix
concrete to thereby strengthen the concrete and obviate or reduce the need to use
reinforcing bars or steel mesh in the concrete. The location at which the reinforcing
fibers are added to the other components of the ready mix concrete is important
because adding these fibers too early in the process presents issues with respect
to conveying the reinforcing fibers along with the rest of the components while
adding the reinforcing fibers too late precludes evenly dispersing the reinforcing
fibers into the ready mix concrete.
Alternatively, the admix or reinforcing fibers may be fed onto the
dry material conveyor
190 through the protective cover, as most clearly
illustrated in FIG. 3. Feeding the reinforcing fibers in this manner is preferably
accomplished through a conveyor
199.
The portable concrete plant
10 of the present invention minimizes the
environmental impact on the area surrounding the portable concrete plant
10
because the discharge boot
150 and the sleeve
194 enables the concrete
truck to be cleanly loaded. In particular, the concrete loading system of the present
invention eliminates or at the very least substantially
