Information
-
Patent Grant
-
6318445
-
Patent Number
6,318,445
-
Date Filed
Friday, June 23, 200024 years ago
-
Date Issued
Tuesday, November 20, 200122 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 164 131
- 164 344
- 164 404
- 164 403
- 164 408
- 134 21
- 134 24
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International Classifications
-
Abstract
A riser topping gathering system and method are disclosed. The system and method are used in gathering riser topping material from the riser cavities of the cope portion of a mold. A capture hood includes high-pressure air outlets and is connected to a duct system, collector and air moving mechanism. The capture hood is moved into contact with the top of the cope mold portion. The air moving mechanism pulls a stream of ambient air over the top of the cope mold portion while high pressure air is pulsed into the riser cavities through the high air pressure outlets. The pulses of high-pressure air activate the riser topping materials and raise them out of the riser cavities and into the path of the ambient air in the capture hood. The moving ambient air carries the riser topping material out of the capture hood and into the duct system. The air and riser topping material is moved to the collector where the riser topping material is separated from the air. The riser topping material may then be gathered from the collector and disposed of or recycled. The cope mold portion may then be moved to another workstation for removal of the risers from the riser cavities.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to casting metal objects in molds that have riser cavities and riser toppings in the riser cavities, and to the problems associated with the use of riser toppings.
2. Description of the Art
In some metal molding processes, such as those used in casting steel railroad wheels, a solid graphite mold is used, with both cope and drag portions. Such molds are designed to be reused after a cast wheel has been removed from the mold. The cope mold portion, that is the top portion, typically has riser cavities. Such riser cavities typically have generally vertically-disposed cylindrical walls, and are open at both the tops and bottoms of the cavities. Prior to casting, a sand coating is typically baked onto parts of the walls of the riser cavities. During casting of the wheel, a reservoir of molten metal forms in the riser cavity attached to the wheel casting to compensate for internal contraction of the casting during solidification. After the metal is poured, a riser topping material is typically placed in the open top of the riser cavity on top of the molten metal in the riser. Riser toppings provide an insulating effect and reduce heat loss from convection and radiation. Compounds that serve as such insulators include powdered graphite, coke breeze, charcoal, rice or oat hulls and various combinations of refractory powders. After the cast wheel is removed from the mold, there is a waste metal riser left in the riser opening, as well as waste riser topping material. Before the cope portion of the mold is used again, the waste riser and waste riser topping material must be removed from the riser cavity, and the baked sand coating must be removed.
In one prior art system, the waste metal riser and waste riser topping material are knocked out of the riser opening by a plunger assembly. In that system, there are brushes attached to solid plungers that are driven through the riser cavities of the cope portion of the mold. The plungers push the waste risers out through the bottoms of the riser cavities, the riser topping materials drop out through the bottoms of the riser cavities, and the brushes clean the cylindrical side walls of the riser cavities, brushing off the baked sand coating on the walls of the riser cavities. In this system, the waste risers and some of the riser topping materials drop through a chute in the mill floor below the apparatus. There are hoppers in the basement under the mill floor and riser knock out station. Deflector bars beneath the mill floor deflect the waste risers to one hopper and allow sand and riser topping to drop to a second hopper. However, quantities of riser topping material also frequently fall to the mill floor. In another prior system, the surface of the cope mold portion is cleaned with high pressure air streams which blow any riser topping materials off of the cope mold portion surface. The waste metal risers may be knocked out in a separate operation and the waster metal risers and riser topping materials may then be gathered from separate hoppers below the mill floor, and the waste metal risers may be recycled. However, quantities of riser topping material also frequently fall to the mill floor. With these prior systems, the riser topping materials, such as the rice hulls, create potential maintenance and safety problems. The hulls or other riser topping material can get into the plant machinery, such as the conveyor, and dust from the riser toppings can get into the workers' eyes, for example. In addition, the waste riser topping material must be gathered up from the mill floor in a labor-intensive operation.
In typical production, the cope mold sections are recycled for reuse after the risers have been pushed out of the riser cavities.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a riser topping gathering system and a method that may be used to gather the riser topping materials. The system and method may also be used to gather other loose materials.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures of the Drawings, like reference numerals identify like components and:
FIG. 1
is a side elevation view of a part of a foundry showing the riser topping gathering system of the present invention in a production line with some other systems of the foundry;
FIG. 1A
is a schematic view of the riser topping gathering station and other stations in the production line of the foundry;
FIG. 2
is a top plan view of a cope portion of a mold;
FIG. 3
is a side elevation of the riser topping gathering apparatus of
FIG. 1
, with a part of the cope mold portion shown in cross-section, and shown with the capture hood in a raised position;
FIG. 4
is a top plan view of the riser topping gathering apparatus of
FIG. 3
;
FIG. 5
is a back elevation of the riser topping gathering apparatus of
FIGS. 2-3
, shown with the duct system removed for clarity of illustration; and
FIG. 6
is a side elevation of part of the riser topping gathering apparatus of
FIGS. 3-5
, shown with the capture hood in a lowered position, and with the capture hood shown in cross-section along line
6
—
6
of
FIG. 5
, and with four of the riser cavities of the cope portion of the mold shown in cross-section, the cross section of the cope mold portion being taken along line
6
—
6
of FIG.
2
.
DETAILED DESCRIPTION
An example of a site in which the present invention has utility is illustrated in side elevation in FIG.
1
and schematically in FIG.
1
A. The illustrated site is a foundry for the production of cast steel railway wheels. It should be understood that this use is presented for purposes of illustration only, and that the present invention is not limited to the illustrated and described site and use unless expressly set forth in the claims.
The illustrated foundry has a station
10
, shown schematically in
FIG. 1A
, for casting the steel railway wheels. The wheels are cast in a two-piece mold, the mold having cope and drag portions. Downstream from the casting station
10
, the cope and drag portions of the mold are separated at a splitter or second station
12
. From this splitter station
12
, the cope portion of the mold is moved along a conveyor
14
. The cope portion of the mold is shown at
17
in FIG.
1
. The illustrated foundry incorporates the present invention: a riser topping gathering station
16
is provided. The cope mold portion
17
is moved along the conveyor
14
from the splitter station
12
to the riser topping gathering station
16
. After passing through riser topping gathering station
16
, the cope portion
17
of the mold passes along the conveyor
14
to one of two riser removal stations
18
. From the riser removal station
18
, the cope mold portion
17
is moved along the conveyor
14
to one or more additional treatment stations, shown schematically at
20
in
FIG. 1A
, where the solid graphite mold surfaces may be cleaned and machined and the riser cavities may be filled with core sand and baked, and the cope mold portion
17
combined with a drag mold portion (not shown). The combination cope and drag mold portions may then be conveyed again to the casting station
10
, and the process repeated until the cope and drag mold portions have gone through several cycles. After a number of cycles, the steel flask parts of the cope and drag mold portions may be recycled and the old graphite may be scrapped or recycled. To achieve maximum efficiency in this manufacturing cycle, it is desirable that the dwell time at any of the non-casting stations
12
,
16
,
18
,
20
be kept to a minimum so that the operations performed at these stations do not slow down the casting operations.
FIG. 2
illustrates an example of a cope mold portion
17
in top plan view, with a flask
22
surrounding a graphite element
23
of the cope mold portion
17
. As shown, the cope mold portion
17
has a top
24
with a plurality of openings
26
in the top
24
. The top
24
of the cope mold portion
17
includes both the top surface of the graphite portion
23
and the top surface of the flask
22
. Each opening
26
in the top is vertically aligned with a riser cavity extending through the height of the cope mold portion. Examples of riser cavities are shown at
28
in
FIGS. 3 and 6
. The cross-section through the cope mold portion
17
in
FIG. 6
is taken along line
6
—
6
of FIG.
2
. In the illustrated embodiment, there are
13
openings corresponding with
13
riser cavities, but it should be understood that the number and position of the riser cavities and openings may vary depending upon the product being cast. The present invention is not limited to any particular number or pattern of riser cavities or openings unless expressly set forth in the claims. The illustrated cope mold portion
17
is the cope portion of a standard re-usable graphite mold, wherein the graphite is bonded into solid form. However, the present invention is not limited to any particular type of mold unless expressly set forth in the claims.
During casting, liquid metal rises in the riser cavities
28
and feeds metal to the casting as the casting solidifies and contracts. To limit heat loss, a riser topping material is placed in each opening
26
of the cope mold portion
17
. Riser toppings provide an insulating effect and reduce heat loss by convection and radiation. Compounds that serve as such insulators include powdered graphite, coke breeze, charcoal, rice or oat hulls and various combinations of refractory powders. As used herein, “riser topping” and “riser topping material” should be understood to include all of these materials, as well as any other material suitable for use for this purpose.
In each riser cavity, the riser eventually solidifies, and remains in the cope mold portion
17
after the cast product has been removed, with the riser topping material resting on top of the metal riser. Examples of solid risers are shown at
30
in
FIGS. 3 and 6
, and riser topping is shown at
32
in
FIGS. 3 and 6
. As shown in
FIG. 3
, when the cope mold portion
17
is received at the riser topping gathering station
16
, there is a quantity of riser topping
32
in the riser cavity
28
and on top of the riser
30
. It should be understood that the other riser cavities
28
also include similar metal risers and similar quantities of riser topping. In each of the riser cavities, there is riser topping
32
between the solid metal riser
30
and the top
24
of the cope mold portion
17
; there may also be some loose riser topping on the surface of the top
24
of the cope mold portion
17
. The present invention provides a system and method for gathering this riser topping material from the cope mold portion.
Since it is desirable that the mold portions be processed quickly for reuse, there is little time for the risers and riser toppings to cool to ambient temperature before reaching the riser topping gathering station
16
. Thus, when the cope mold portion
17
reaches the riser topping gathering station
16
, the metal risers
30
are still typically at a high temperature, and the riser topping
32
is also typically at a high temperature. The riser topping
32
may be burning when the cope mold portion
17
reaches the riser topping gathering station
16
, and the components of the riser topping gathering station
16
should be capable of being exposed to this high temperature material without suffering catastrophic damage.
In addition to the cope mold portion
17
with metal risers
30
and riser topping
32
in the riser cavities
28
, the riser topping gathering system
34
of the present invention includes a high pressure air system
36
, a capture hood
38
for gathering riser topping material from the cope mold portion
17
, a primary collector
40
for collecting riser topping material, a duct system
42
and an air moving mechanism
44
. All of these elements are shown schematically in FIG.
1
A. For high temperature applications, the primary collector
40
should be made of non-flammable components; for other applications, a fabric filter dust collector may be employed.
An example of a high-pressure air system is shown in the illustrated embodiment. The illustrated high-pressure air system
36
comprises a plant supply of high-pressure air
45
, such as available from a compressor or the like, and a compressed air tank
46
. The compressed air tank
46
is connected to receive compressed air from the plant supply
45
through a suitable conduit
48
. Another conduit
50
is connected to receive high-pressure air from the compressed air tank
46
through a valve
52
. Suitable couplings and connectors are used in the illustrated embodiment to connect the tank
46
to the valve
52
and the valve
52
to the receiving conduit
50
. In the illustrated embodiment, the receiving conduit
50
delivers the high-pressure air pulses to a manifold
54
. The illustrated manifold
54
is connected to a plurality of flexible air hoses
55
.
For the elements of the illustrated high-pressure air system
36
, commercially available components may be used. For example, the compressed air tank
46
may be purchased from McMaster-Carr, of Atlanta, Ga., Chicago and Elmhurst Ill. and other locations, ASME-Code Horizontal Pressure Steel Tank part no. 9888K19. The valve
52
is a commercially available 1½ inch “Goyen” double diaphragm valve, available from Wheelabrator Canada, Inc. of Milton, Ontario, Canada, part no. 620337. The illustrated control box
56
is also commercially available from Wheelabrator Canada, Inc., part nos. RCA6V53, RCA5D2. It should be understood that all of these elements are identified for purposes of illustration only. The identified diaphragm valve and control box are the type that are typically used in bag houses in factories to provide short bursts of air during a cleaning cycle in the bag house. Other devices that provide periodic short bursts of high-pressure air may be used. In addition, it may be desirable to use another source of high-pressure air that delivers the air over longer times or in different manners. The present invention is not limited to any type of high pressure air delivery system or any particular components for such a system unless expressly set forth in the claims.
In the illustrated embodiment, the control box
56
is connected to receive electrical input from a programmable logic controller (PLC). A PLC is shown schematically at
57
in
FIGS. 3-5
. The PLC
57
may be connected to receive inputs from various sources, such as a limit switch (not shown) that senses when the cope mold portion
17
is in position below the capture hood
38
. A commercially available PLC may be used. It is expected that the supplier would be consulted for selection of an appropriate model of component. A standard PLC with standard logic may be programmed by one skilled in the programming art, such as an electrical engineer, or more sophisticated programming could be developed if desired. It should be understood that the use of a PLC is identified for purposes of illustration only, and that the invention is not limited to use of PLCs, or to any particular program, computer or PLC.
In the illustrated embodiment, the receiving conduit
50
includes a standard flexible 1½ inch diameter hose with a length of about 7 feet. The manifold is a steel pipe, 1½ inch diameter and 5 feet long. The illustrated manifold has
14
holes bored through its outer wall; at each hole a pipe coupling is welded to the pipe. These couplings receive barbed hose couplings that serve as connecting mechanisms for the flexible air hoses
55
. One end of each flexible air hose
55
is connected to receive high-pressure air through one opening in the manifold. One end of the manifold is connected to the conduit
50
, and the opposite end
58
is closed with an end cap welded to the pipe. Thus, high pressure air can flow from the compressed air tank
46
through the valve
52
to the conduit
50
, through the conduit
50
to the manifold
54
, and through the manifold to each of the flexible air hoses
55
. Each air hose
55
has a second end that is connected to a high-pressure air outlet
60
, shown in FIG.
6
. The high-pressure air outlets
60
are all part of the capture hood
38
of the riser topping gathering system.
In the illustrated embodiment, as shown in
FIG. 6
, each high-pressure air outlet
60
comprises a nozzle made by drilling a ⅛-inch diameter hole in a standard ¾-inch diameter steel cap. It should be understood that other air outlets or nozzles may be used, such as conical-shaped nozzles or small diameter conduits, for example, and the invention is not limited to any particular shape or material for the air outlets unless expressly set forth in the claim.
The above description of elements from the tank to the high pressure air outlets
60
should be understood as providing an example only of a system for delivering high pressure air to the capture hood. The invention is not limited to any of the elements described unless expressly set forth in the claims.
In the illustrated embodiment each end cap defining the high-pressure air outlet
60
is connected to an upwardly extending ¾-inch pipe nipple
62
. The upper end of each pipe nipple
62
is received in a ¾-inch pipe coupling
64
. Each pipe coupling
64
is received in a bore in a top member
66
. The top member
66
comprises a ¼-inch thick steel plate in the illustrated embodiment, and each pipe coupling
64
is welded to the top surface of the steel plate. Hose connectors
68
extend upward from most of the pipe couplings
64
, above the top surface of the top plate member
66
; one or more of the high pressure air flow paths may include an elbow
70
between the coupling
64
and the hose connector
68
. Each flexible air hose
55
is attached to one of these hose connectors
68
to deliver air to the high-pressure air outlets
60
. It should be understood that this assembly is provided as an example only and that the invention is not limited to use of these elements unless expressly called for in the claims. Other means may be used to secure the high-pressure air outlets in predetermined positions on the capture hood.
The capture hood
38
also includes two sides
72
,
74
with tops
76
and bottoms
78
. In the illustrated embodiment, each side member
72
,
74
comprises a steel channel that runs along substantially the entire length of the capture hood
38
. The interior sides of each channel is connected to two angles used to mount the capture hood top member
66
to the side members
72
,
74
. These two angles are shown at
73
and
75
in FIG.
6
.
The bottom
78
of each side member
72
,
74
is connected to a gasket assembly
80
. Each gasket assembly
80
runs the length of the respective side member
72
,
74
. Each illustrated gasket assembly includes a steel top plate ⅛ inch by 2 inches by 4 feet 7½ inches, and a compressible rubber gasket strip 1 inches by 2 inches by 4 feet 7½ inches. The illustrated gasket strip, shown at
81
in
FIG. 8
, is commercially available from Gaskets, Inc. of Rio, Wis., part no. G/1-SHS-5, silicone closed cell foam. The gasket assembly is removably attached to each side member
72
,
74
through bolts and wing nuts in the illustrated embodiment. It should be understood that the details of the side members and gaskets are provided by way of example only, and that the present invention is not limited to the described side members and gasket assemblies or to use of such elements unless expressly called for in the claims. In addition, while use of the gasket assemblies generally improves efficiency by sealing parts of the capture hood against ambient air, the system could be operated without this seal if desired. However, as described below, the gasket assembly also seals against the cope mold portion to prevent riser topping material from exiting into the plant environment.
Generally, the high pressure air outlets should be positioned on the capture hood
38
so that high pressure air is efficiently delivered into each riser cavity, and so that the means selected for delivering the high pressure air into the riser cavities do not damage and are not damaged by the top
24
of the cope mold portion
17
. In the illustrated embodiment, these ends are achieved by positioning a high pressure air outlet vertically over each riser cavity and by positioning the high pressure air outlets so that they do not extend below a horizontal plane through the bottoms
78
of the side members
72
,
74
. However, variations are possible: for example a flexible nozzle could be provided that could extend into the riser cavity; vertical movement could be possible to extend the high pressure air outlets down closer to or into the riser cavities, or one high pressure air outlet could be positioned or moved to deliver high pressure air to more than one riser cavity. Other variations are possible and within the scope of the invention unless expressly excluded.
Generally, it is desirable that the capture hood
38
or at least parts of it be vertically movable to accommodate cope mold portions
17
of different heights and to be raised out of the path of the cope mold portion when it is received at the riser topping gathering station
16
and to be lowered into an operational position juxtaposed with the top of the cope mold portion when the cope mold portion is in position at the station
16
. In the illustrated embodiment, vertical movement and support of the capture hood
38
is provided by a stationary frame
82
and a vertically movable frame
84
. Examples of a stationary frame
82
and vertically-movable frame
84
are shown in the drawings and described below; however, it should be understood that these structures are illustrated and described by way of example only, and that the invention is not limited to use of the illustrated structures unless expressly set forth in the claims. In addition, it should be understood that the invention is not limited to a vertically movable capture hood unless expressly set forth in the claims. Other structures are possible: for example, the conveyor
14
may include structures that allow the cope mold portion to be raised to contact the capture hood, or the system could be designed so that the capture hood or cope mold portion moves horizontally over or under the other.
In the illustrated embodiment, the vertically-movable frame
84
includes a pair of outer channel members
86
,
88
extending transversely across and connected to the tops
76
of the side members
72
,
74
of the capture hood
38
. A pair of closely spaced central channel members
90
,
92
also extend transversely across and are connected to the tops
76
of the side members
72
,
74
of the capture hood
38
. The outer channel members
86
,
88
are each connected to a pair of vertical steel braces
94
,
96
that extend upward from the outer channel members
86
,
88
. Each vertical brace
94
,
96
is connected to a vertical plate
97
that is connected to a vertical angle
98
. The corner of each angle
98
is exposed and runs vertically. The tops of opposite vertical plates
97
may be connected by a longitudinal brace
100
. In
FIG. 4
, the longitudinal braces
100
are removed for clarity of illustration.
The central channels
90
,
92
are pivotally connected to a vertical movement mechanism. In the illustrated embodiment, the vertical movement mechanism is an air cylinder. It should be understood that this mechanism is shown for purposes of illustration only, and that the invention is not limited to use of an air cylinder; a hydraulic cylinder could be used or some combination of mechanical elements could be used to raise and lower the capture hood.
As shown schematically in
FIG. 3
, the air cylinder
102
may be connected to the plant air supply
45
. Also as shown in
FIG. 3
, one end of the air cylinder
102
is pivotally connected to the central channel members
90
,
92
and the other end of the air cylinder
102
is pivotally connected to a transverse channel member
104
that is part of the stationary frame
82
. The air cylinder
102
may be a commercially available one, such as one available from Parker-Hannifin Corporation of Cleveland, Ohio, Series 2A Heavy Duty Pneumatic Cylinder, 5 inch bore, 14 inch stroke, with appropriate mounting hardware. This air cylinder is identified for purposes of illustration only; the invention is not limited to this particular air cylinder or to the use of air cylinders unless expressly set forth in the claims.
In the illustrated embodiment, the air cylinder
102
is used to move the capture hood
38
and vertically-movable frame vertically toward and away from a cope mold portion
17
on the conveyor
14
below the capture hood
38
. To guide the vertical movement of the vertically movable frame
84
and capture hood
38
, the stationary frame
82
includes sets of V-rollers
106
mounted on mounting brackets
108
. The mounting brackets
108
are fixed to horizontal channels
110
of the stationary frame
82
. The vertical angles
98
of the vertically movable frame
84
travel in the grooves of the V-rollers. The V-rollers are commercially available from the Osborne International unit of Jason Incorporated of Cleveland, Ohio as stud style roller part no. VLR-2-½. It should be understood that this guiding system is provided by way of example only, and that the invention is not limited to these components unless expressly set forth in the claims.
In the illustrated embodiment, the stationary frame
82
also includes a horizontal plate
112
that is fixed to the tops of the horizontal channels
110
. The horizontal plate
112
supports the compressed air tank
46
and control box
56
. It should be understood that the invention is not limited to providing such a plate unless expressly set forth in the claims.
The capture hood
38
of the illustrated riser topping gathering system
34
also includes a pair of brackets
114
,
116
attached to one end of the side members
72
,
74
, and a transverse mounting angle
118
that extends across back of the capture hood from one side member
72
to the other side member
74
. The brackets
114
,
116
and angle member
118
serve to provide mounting supports for the duct system
42
.
As shown in
FIGS. 3-4
and
6
, a funnel-shaped duct member
120
is mounted to the angle member
118
and brackets
114
,
116
at one end of the capture hood
38
. The funnel shaped duct member
120
extends transversely across the entire capture hood
38
, from side member
72
to side member
74
, from below the bottoms
78
of the side members
72
,
74
to the top member
66
of the capture hood. This end of the capture hood defines an exit for ambient air to travel from the capture hood to the duct system
42
; this ambient air exit is shown at
122
in FIG.
6
. It should be understood that the ambient air exit
122
also serves as an exit for high pressure air that has been delivered into the riser cavities and for riser topping material that has been lifted out of the riser cavities. Thus, the expression “ambient air exit” should be understood to include ambient air and may also include high pressure air and riser topping material that exits the capture hood into the duct system, as in the illustrated embodiment of the invention.
The capture hood
38
also has an ambient air entry
124
opposite from the ambient air exit
122
. The ambient air entry
124
is separated from the ambient air exit
122
by the two gasket assemblies
80
. When the capture hood
38
is lowered to place the gaskets of the gasket assemblies
80
against the top surface
24
of the cope mold portion
17
as shown in
FIG. 6
, an air flow path
125
is defined from the ambient air entry
124
into the capture hood
38
below the top member
66
and over the top
24
of the cope mold portion. In the illustrated embodiment a curved transverse vane
126
is provided across the capture hood at the ambient air entry
124
to guide the ambient air stream into the interior of the capture hood. It should also be understood that the term “ambient air” is used herein to refer to the air in the plant around the capture hood
38
, it should be understood that the term is not limited to such plant air, but may include, for example, air delivered to the ambient air entry
124
from a source such as an air treatment or cooling system or air from outside the plant, or combinations of such sources of air.
As shown in
FIG. 6
, the airflow path
125
within the capture hood
38
expands from the ambient air entry
124
toward the interior of the capture hood. That is, the transverse cross-sectional area of the airflow path
125
is smallest at the ambient air entry
124
and increases toward the center of the capture hood
38
. The cross-sectional area of the airflow path is then constant up to the ambient air exit
122
.
As shown in
FIG. 1
, in the illustrated embodiment the duct system
42
leads from the ambient air exit
122
of the capture hood
38
to the primary collector
40
. From the primary collector
40
, in the illustrated embodiment the duct system
42
leads to a secondary collector
130
and from the secondary collector
130
to the air moving mechanism
44
. The air moving mechanism
44
can be connected to either the duct system
42
or the collector
40
to move an ambient air stream into the ambient air entry
124
of the capture hood, though the ambient air flow path
125
, out the ambient air exit
122
, into the duct system
42
and to the collector
40
.
At least part of the duct system should be a flexible duct to allow at least part of the duct system to move with vertical movement of the capture hood. As shown in
FIG. 1
, the duct section shown at
131
is flexible. A suitable flexible duct section may comprise a metal hose. Examples of suitable flexible metal hoses include 5 foot lengths of 6 inch inner diameter galvanized medium weight metal hose #5495K35, 6 inch inner diameter standard gauge stainless steel hose #5241K72 or 6 inch inner diameter heavy gauge stainless steel hose, all available from McMaster-Carr, of Atlanta, Ga., Chicago and Elmhurst Ill. and other locations. The other sections of the duct system may be made of standard metal materials. All of these elements are identified for purposes of illustration only, and the present invention is not limited to any size or type of element unless expressly called for in the claims. Generally, the materials selected should be capable of withstanding the transport of high temperature air and riser topping material. The sizes and shapes of the ducts may be selected to control the speed of movement of the stream of air and riser topping material to maximize the useful life of the duct system or for some other desired parameter.
The primary collector
40
may be any commercially available separator device that meets the technical requirements for design parameters such as pressure and volume. In addition, for a system gathering high temperature materials, the primary collector
40
should be of all metal construction to reduce the risk of fire. For other applications, if there is no risk of fire, a fabric filter dust collector may be used. The primary collector
40
shown in
FIG. 1
has a collection chute
146
leading to a discharge collector or hopper
148
that may be provided beneath the floor of the factory, for example, or in any other suitable location. The air stream may be drawn off from the primary collector
40
through an exhaust duct and delivered by that duct to an inlet of the secondary collector
130
for further processing. The secondary collector
130
may comprise a standard baghouse dust collector, utilizing a plurality of filter bags (not shown) through which the air stream is drawn. The waste riser topping material and dust may then fall through a secondary discharge collection chute
150
to a discharge collector, which may be common with the discharge collector
148
of the primary collector
40
.
An example of a suitable primary collector is a commercially available collector from Airotech, Inc. of Pittsburgh, Pa., Model M1060WHS (Special) No. 2-6 Tubular Dust Collector, Organ Pipe Design. It should be understood that this primary collector is identified for purposes of illustration only, and that the invention is not limited to this particular collector or to this particular type of collector unless expressly set forth in the claims. For example, a commercially available cyclonic collector could also be used.
A suitable secondary collector
130
is available from American Vacuum Company of Skokie, Ill., type 48×96 Cyclone (Model 48FR96). However, the invention is not limited to this device or this type of device unless expressly set forth in the claims.
The illustrated system using a primary collector
40
and secondary collector
130
may be modified by omitting some elements, such as by using only a single collector, or a two stage single collector, or the like. However, if there is a risk of fire, the collector or collectors used should be non-flammable and suitable for high temperature applications. As used herein, “collector” encompasses a single device or apparatus by which the riser topping materials may be separated or filtered from the air stream and collected or accumulated together, as well as more than one device or apparatus for accomplishing this result.
The air-moving mechanism
44
may comprise a single fan and drive motor, drawing clean air from the secondary collector
130
through an outlet duct and discharging the clean air through a clean air outlet duct
152
. The preferred air flow velocities and volumetric flow rates are described below following the description of the method of the present invention. A suitable drive fan and motor are available from American Vacuum Company, Model 1214-3-1-AD cast centrifugal vacuum exhauster direct driven by a 40 hp Reliance TEFC premium efficiency motor. It should be understood that other air moving mechanisms may be used, and that the invention is not limited to this mechanism or this type of mechanism unless expressly set forth in the claims.
The riser topping gathering system may be made by assembling the above-described components.
The riser topping gathering system may be used in the method of the present invention. The method involves providing a cope mold portion
17
with a top
24
having one or more openings
26
and a riser cavity
28
aligned with each opening
26
. A metal riser
30
is in the riser cavity
28
and riser topping material
32
is above the metal riser
30
. After the presence of the cope mold portion has been sensed and a signal sent to the PLC
57
, the air cylinder
102
is activated to lower the capture hood
38
and vertically movable frame
84
downward until the gaskets
81
rest on the top
24
of the cope mold portion
17
. The PLC
57
may then signal the controller
56
to activate the valve
52
. Once the valve
52
is activated high pressure air from the compressed air tank
46
is delivered in a burst or pulse from the valve
52
to the conduit
50
, and from the conduit
50
to the manifold
54
. From the manifold, the burst or pulse of high-pressure air is delivered to the air hoses
55
, and from the air hoses, the bursts or pulses of high-pressure air exit through the high pressure air outlets
60
. The high pressure air is delivered at around
80
psi from the tank
46
as are the bursts of air delivered from the high pressure air outlets
60
. It should be understood that although the expression “high pressure air” is intended to include air at pressures of around 80 psi, the expression is not limited to that pressure. The expression “high pressure air” should be understood to include typical plant compressed air systems operating at 80-120 psi., and should also be understood to encompass air pressures that can move into the riser cavities and activate the riser topping material in the riser cavities and raise the activated riser topping material out of the riser cavities and into the air flow path
125
.
The high-pressure air pulses delivered from the outlets
60
are shown in
FIG. 6
, and some have been identified with reference number
160
. As can be seen, the high pressure air pulses
160
travel down into the riser cavities
28
and are reflected back up into the air flow path
125
. This air stream
160
activates and raises the riser topping material
32
out of the riser cavities
28
. In addition, the high-pressure pulses are preferably of suitable pressure to cause riser topping material on the top surface of the cope mold portion to become air-borne.
In the illustrated embodiment, the PLC
57
and control box
56
are set to operate the valve
52
in short pulses of 50 milliseconds. The system has been found to be effective in gathering rice hull riser topping materials when four pulses of 80 psi air, each lasting 50 milliseconds, with two seconds between pulses. The first pulse is released two seconds after the capture hood
38
contacts the top
24
of the cope mold portion
17
, and the capture hood
38
is raised two seconds after the fourth pulse stops.
Throughout the entire time that the capture hood
38
is in contact with the cope mold portion
17
, the air moving mechanism
44
is operating to pull a stream of ambient air into the ambient air entry
124
of the capture hood
38
, through the air flow path
125
, out the ambient air exit
122
, into the duct system
42
, though the collectors
40
,
130
and to move the air out through the outlet duct
152
. This stream of ambient air is shown generally at
162
in FIG.
6
. As can be seen from
FIG. 6
, as the high pressure air stream
160
lifts the riser topping material
32
into the air flow path
125
, the lower pressure ambient air stream
162
carries or moves the riser topping material
32
out through the ambient air exit
122
and into the duct system
42
. The riser topping material
32
is carried with the air stream
162
through the duct system
42
and is separated from the air stream at the collectors
40
,
130
. The separated riser topping material
32
drops through the collection chutes
146
,
150
and is gathered in the discharge collector
148
.
At the end of the cycle, the capture hood
38
and vertically movable frame
84
may be raised through operation of the air cylinder
102
. The cope mold portion
17
may then be moved downstream to the next workstation
18
for removal of the metal risers.
Several of the details of the illustrated embodiment of the invention relate to the fact that the riser topping material is at a high temperature when gathered. When the high pressure air is pulsed into the system, sparks are created in the ambient air flow path
125
. If not accounted for, these sparks can give rise to problems in the plant: a fire ball could be created that could escape to the plant; the standard bag house collector
130
could be damaged from the sparks and from material ignited by the sparks; and the fire could create high pressure that could force burning material out of the ambient air inlet
124
. These problems are addressed in the illustrated embodiment in several ways. First, the total air volume moving through the capture hood
38
exceeds the volume of air pulsed into the system through the outlets
60
; that is, the volumetric flow rate of the ambient air stream exceeds the volumetric flow rate of the high pressure air pulses. Second, the top member
66
of the collection hood
38
is shaped to provide a small cross-section ambient air entry and an expanding transverse cross-sectional area within the capture hood so that a high velocity ambient air stream is at the ambient air entry
124
so that air, dust, sand and riser topping material does not back flow out through the ambient air entry into the plant environment. This design should also increase the collection efficiency by controlling the velocity and pressure of the ambient air stream
162
as it enters and travels through the capture hood. Third, the timing sequence described above provides several advantages: the initial flow of ambient air through the path
125
picks up riser topping material from the top surface
24
of the cope mold portion
17
to create a clean environment in the path
125
from the air entry
124
to at least the area of maximum cross-section before the high pressure air is pulsed into the system; thus, the timing sequence serves to minimize the amount of material that could be ignited by the sparks caused by the high pressure air pulses. In addition, the two second delay before commencing the high pressure air pulses allows time for the capture hood
38
to seal against the top
24
of the cope mold portion
17
to ensure that burning material does not escape into the plant environment; and the two second delays between high pressure pulses allow for some cooling of the system as ambient air is continuously drawn through the capture hood, duct system and collectors.
In addition, as shown in
FIGS. 3 and 6
, since the bottom of the funnel-shaped duct member
120
is below the level of the gaskets
81
and below the level of the top
24
of the cope mold portion
17
, all of the ambient air stream
162
should enter the duct
120
, and no burning material should enter the plant environment. The two-second delays between high pressure air pulses allows for a cooling ambient air stream to be drawn into the system between pulses. And in the illustrated embodiment, the air moving mechanism
44
operates continuously to cool the primary collector
40
and the duct system
42
.
The system of the present invention allows for efficiencies in the sizing and operation of the air-moving mechanism. With the pulsing high pressure air streams, smaller air velocities and volumes for the ambient air streams
162
are needed. Generally, the high pressure air pulses move the riser topping material out of crevices and off of the top
24
of the cope mold portion and into the path of the air stream
162
above the top
24
of the cope mold portion
17
wherein the airborne riser topping materials may be moved more efficiently.
Generally, the air moving mechanism
44
will be selected and set to operate at speeds depending on factors such as the density and particle size of the riser topping material. In addition, the air moving mechanism can be selected and set to operate, in coordination with the size of ductwork, to move the air and riser topping material through the duct system at speeds that reduce wear and tear on the duct system. The ambient air velocities may be on the order of about 4,200 feet per minute at the ambient air intake
124
and at about 2,100 feet per minute at the tallest cross section of the capture hood
38
. These air velocities are generally substantially less than one would need to pick up static riser topping material from the top of the cope mold portion. Capital costs can thus be saved in using a smaller fan and smaller ducts and collector or collectors. Operational costs may also be saved since the fan is run at a lower horsepower when used in combination with the high pressure pulses.
At the above-described velocities, the riser topping gathering system may also advantageously collect heavier bulk density materials along with the riser topping materials. The pulses of high pressure air can activate loose core sand and dust in the riser cavity and on the top surface of the cope mold portion, and lift these materials into the ambient air stream
162
. Thus, the ambient air stream
162
flowing through the capture hood and entering the duct system
42
may carry or move the high pressure air delivered by the high pressure air oulets
60
, the ambient air that enters through the ambient air entry
124
, the riser topping material
32
, sand and dust. A volumetric flow rate of about 2400 cubic feet per minute for the ambient air stream should carry the riser topping material and the heavier sand. However, it should be understood that the present invention is not limited to a system or method that gathers all of the riser topping, sand and dust unless expressly set forth in the claims. In addition, the invention is not limited to any particular velocity or volumetric flow rate unless expressly set forth in the claims.
It should be understood that the principles of the present invention may also be applied to collection of other loose material, at this station in the production system as well as at other stations. For example, it may be desirable to apply the principles of the present invention to a loose material gathering system and method employed to clean the assembled mold before it enters the casting station.
While only specific embodiments of the invention have been described and shown, it is apparent that various alterations and modifications can be made therein. For example, for low temperature applications, it is apparent that several of the fire safety and cooling features could be modified or eliminated. It is, therefore, the intention in the appended claims to cover all such modifications and alterations as may fall within the scope and spirit of the invention.
Claims
- 1. A gathering system comprising:a cope mold portion having a top with an opening, a riser cavity aligned with the opening in the top and extending down from the top, a solid metal riser in the riser cavity and riser topping in the riser cavity between the solid metal riser and the top of the cope mold portion; a high-pressure air system; a capture hood for gathering material from the cope mold portion, the capture hood overlying at least part of the cope mold portion and including an ambient air entry, an ambient air exit, an ambient air flow path over the top of the cope mold portion, and a high pressure air outlet connected to the high pressure air system and positioned to deliver high pressure air into the riser cavity of the cope mold portion, the high pressure air outlet being separate from the ambient air exit; a collector; a duct system extending from the ambient air exit of the capture hood to the collector; and an air moving mechanism connected to at least one of the duct system and the collector for moving an ambient air stream into the ambient air entry of the capture hood, through the ambient air flow path over the top of the cope mold portion, through the ambient air exit of the capture hood, into the duct system and to the collector.
- 2. The gathering system of claim 1 wherein the cope mold portion has a plurality of riser cavities and the top of the cope mold portion has a plurality of openings, each opening aligned with one riser cavity, and wherein the capture hood has a plurality of high pressure air outlets positioned to deliver high pressure air into one riser cavity of the cope mold portion.
- 3. The system of claim 2 wherein the high pressure air path includes a manifold and a plurality of air hoses leading from the manifold, each air hose leading from the manifold to one high pressure air outlet.
- 4. The system of claim 1 wherein the capture hood has two sides with tops and bottoms and a top member, the bottom of each side including a gasket positioned against the top of the cope mold portion, the ambient air entry being between the gaskets and the ambient air exit being between the gaskets and spaced from the ambient air entry, the ambient air flow path being between the top member of the capture hood and the top of the cope mold portion.
- 5. The system of claim 4 wherein the cross-sectional area of the ambient air entry is less than the cross-sectional area of the ambient air exit and wherein the cross-sectional area of the ambient air flow path increases between the ambient air entry and the ambient air exit.
- 6. The system of claim 1 wherein the high-pressure airflow path includes a valve downstream of the high-pressure air source.
- 7. The system of claim 1 further including a stationary frame and a vertically movable frame, the capture hood being connected to the vertically movable frame.
- 8. A method of gathering riser topping material from a cope portion of a mold comprising the acts of:providing a cope mold portion with a top having an opening and a riser cavity aligned with the opening, a metal riser in the riser cavity and riser topping material above the metal riser; moving a first stream of air over at least a part of the top of the cope mold portion; delivering a second air stream into the riser cavity to raise at least a portion of the riser topping material out of the riser cavity and into the path of the first air stream; the first air stream moving the raised riser topping material away from riser cavity.
- 9. The method of claim 8 wherein the second air stream is delivered into the riser cavity in a pulse simultaneously with movement of the first air stream.
- 10. The method of claim 8 wherein the second air stream is delivered in a series of separate pulses.
- 11. The method of claim 8 wherein the first air stream is moved from a time before the first pulse until a time after the last pulse of the series of pulses.
- 12. The method of claim 10 wherein the second air stream is pulsed into one riser cavity for about 50 milliseconds and then stopped for about 2 seconds, pulsed again for about 50 milliseconds into the same riser cavity and then stopped for about 2 seconds, pulsed again for about 50 milliseconds into the same riser cavity and then stopped for about 2 seconds, and then pulsed again for about 50 milliseconds into the same cavity and then stopped, the first air stream moving throughout the pulses of the second air stream.
- 13. The method of claim 12 wherein the cope mold portion is then moved to a downstream workstation.
- 14. The method of claim 13 further including the act of casting a steel railway wheel in the mold before gathering the riser topping material.
- 15. The method of claim 8 wherein the cope mold portion has a plurality of riser cavities and wherein the method includes the act of delivering an air stream into each riser cavity.
- 16. The method of claim 8 wherein the first air stream has a lower pressure than the second air stream.
- 17. The method of claim 8 further including providing a capture hood and moving the capture hood over the top of the cope mold portion, and wherein the acts of moving the first stream and pulsing the second air stream take place after the capture hood is moved over the top of the cope mold portion.
- 18. The method of claim 8 wherein the first air stream moves at a velocity of at least 2000 feet per minute over at least part of the top of the cope mold portion.
- 19. The method of claim 18 wherein the first air stream moves at a velocity of between about 2,100 and 4,200 feet per minute over the top of the cope mold portion.
- 20. The method of claim 8 wherein the first air stream includes riser topping material, sand and dirt.
US Referenced Citations (5)
Foreign Referenced Citations (4)
Number |
Date |
Country |
1508609 |
Feb 1971 |
DE |
2222794-A |
Mar 1990 |
GB |
2222794 |
Mar 1990 |
GB |
6-91348 |
Apr 1994 |
JP |