U.S. patent application number 12/111835 was filed with the patent office on 2008-09-25 for scrap melter and impeller therefore.
Invention is credited to Paul V. Cooper.
Application Number | 20080230966 12/111835 |
Document ID | / |
Family ID | 32070173 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080230966 |
Kind Code |
A1 |
Cooper; Paul V. |
September 25, 2008 |
SCRAP MELTER AND IMPELLER THEREFORE
Abstract
A device for submerging scrap metal includes: (a) a drive
source, (b) a drive shaft having a first end and a second end, the
first end being connected to the drive source, and (d) an impeller
connected to the second end of the drive shaft, the impeller
preferably having two or more outwardly-extending blades.
Preferably, each of the blades has a portion that directs molten
metal at least partially downward. The impeller design leads to
lower operating speeds, lower vibration, longer component life and
less maintenance. Additionally, the impeller preferably has a
connective portion. The connective portion is used to connect the
impeller to the shaft and preferably comprises a nonthreaded,
tapered bore extending through the impeller.
Inventors: |
Cooper; Paul V.;
(Chesterland, OH) |
Correspondence
Address: |
SQUIRE SANDERS & DEMPSEY LLP
TWO RENAISSANCE SQUARE, 40 NORTH CENTRAL AVENUE, SUITE 2700
PHOENIX
AZ
85004-4498
US
|
Family ID: |
32070173 |
Appl. No.: |
12/111835 |
Filed: |
April 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10827941 |
Apr 19, 2004 |
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12111835 |
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09649190 |
Aug 28, 2000 |
6723276 |
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10827941 |
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Current U.S.
Class: |
266/236 ;
222/594 |
Current CPC
Class: |
F27D 27/00 20130101;
C21C 5/527 20130101; C21C 1/06 20130101; F27B 3/045 20130101; Y02P
10/20 20151101; Y02P 10/216 20151101; C21C 5/5211 20130101 |
Class at
Publication: |
266/236 ;
222/594 |
International
Class: |
B22D 41/005 20060101
B22D041/005; B22D 41/00 20060101 B22D041/00 |
Claims
1. A device for generating a downward and radial stream of molten
metal in a scrap melter, the device including: (a) a drive source;
(b) a drive shaft having a first end and a second end, the first
end connected to the drive source; and (c) an impeller connected to
the second end of the drive shaft, the impeller having two or more
outwardly extending blades, at least one blade having a leading
face, the leading face including a vertical lip and a portion that
directs molten metal at least partially downward, the impeller
having a hub wherein each blade extends outwardly from the hub by
at least 10''.
2. The device of claim 1 wherein the impeller has four blades.
3. The device of claim 2 wherein the impeller has an overall length
of at least 28'' and an overall width of at least 28''.
4. The device of claim 2 wherein each blade has a leading face
portion that includes an angled surface and a trailing face that is
vertical.
5. The device of claim 1 wherein a connective portion is formed in
the impeller, the connective portion connecting the impeller to the
drive shaft, the connective portion comprising a tapered,
non-threaded bore extending through the impeller.
6. The device of claim 5 which further includes a nut and wherein
the second end of the drive shaft has a threaded section that is
positioned beneath the impeller; the nut being threaded onto the
threaded section to connect the impeller to the drive shaft.
7. The device of claim 1 wherein the portion that directs molten
metal at least partially downward is an angled surface.
8. The device of claim 7 wherein the angled surface is formed at a
45.degree. angle.
9. The device of claim 1 wherein each blade includes a portion that
directs molten metal at least partially downward.
10. The device of claim 1 wherein the impeller has an overall
length of at least 28''.
11. The device of claim 1 wherein each blade has a height of
between 6'' and 7''.
12. The device of claim 1 wherein the hub is a 8'' square in plan
view.
13. The device of claim 1 wherein the leading face includes a
surface that is angled to direct molten metal in a partially upward
direction.
14. The device of claim 1 wherein the impeller has a top surface
and a trailing surface, and a recess formed from the top surface to
the trailing surface.
15. The device of claim 1 wherein each blade includes a vertical
lip.
16. The device of claim 1 wherein the impeller has two or more
blades, and wherein each blade has a leading face portion that
includes an angled surface and a trailing face that is
vertical.
17. A device for generating a downward and radial stream of molten
metal in a scrap melter, the device including: (d) a drive source;
(e) a drive shaft having a first end and a second end, the first
end connected to the drive source; and (f) an impeller connected to
the second end of the drive shaft, the impeller having two or more
outwardly extending blades, at least one blade including a vertical
face that directs molten metal at least partially outward from the
impeller, wherein the blade has a square cross section, and wherein
the impeller has a hub and each blade extends outward from the hub
by at least 10''.
18. The device of claim 17 wherein the impeller has four
blades.
19. The impeller of claim 17 wherein the impeller is in the shape
of a cross.
20. The device of claim 17 wherein the vertical face of each blade
is at least 6 inches in height.
21. The device of claim 17 wherein the vertical face of each blade
is more than 4 inches in height.
22. The device of claim 17 wherein at least one blade includes a
surface that is angled to direct molten metal in a partially upward
direction.
23. The device of claim 17 wherein each blade has a vertical
surface and each blade further includes a surface that is angled to
direct molten metal in a partially upward direction.
24. A device for generating a downward and radial stream of molten
metal in a scrap melter, the device comprising: a drive source; a
drive shaft having a first end connected to the drive source and a
second end; and an open impeller connected to the second end of the
drive shaft for circulating molten metal, the impeller comprising:
a hub; three or more blades extending outwardly from said hub,
there being spaces between the blades, wherein at least one of said
three or more blades includes a leading face with an angled surface
for directing molten metal at least partially in a downward
direction and a trailing face, and wherein at least one of said
three or more blades includes a leading face with a vertical
surface for directing molten metal at least partially in a radially
outward direction and a trailing face. the hub including a
non-threaded tapered bore for receiving an end of a drive
shaft.
25. The device of claim 24 wherein each of the blades includes an
angled surface.
26. The device of claim 24 wherein each of the blades includes a
vertical surface.
27. The device of claim 24 wherein the trailing face is
vertical.
28. The device of claim 24 wherein the impeller has a top surface
and a recess formed from the top surface to the trailing
surface.
29. The device of claim 24 wherein each blade has a height and
width, the height being less than four times the width.
30. A device for melting scrap metal, the device comprising: (a) a
vessel containing molten metal; and (b) a scrap melter positioned
in the vessel, the scrap melter comprising: (i) a drive source;
(ii) a drive shaft having an first end and a second end, the first
end being connected to the drive source; and (iii) an impeller
connected to the second end of the drive shaft, the impeller having
two or more outwardly extending blades, at least one blade having a
leading face, the leading face including a vertical lip portion and
a portion that directs molten metal at least partially downward,
the impeller having a hub wherein each blade extends outwardly from
the hub by at least 10''.
31. The device of claim 30 wherein the leading face portion that
directs molten metal at least partially downward is an angled
surface.
32. The device of claim 31 wherein the angled surface is formed at
a 45.degree. angle.
33. The device of claim 30 wherein the impeller has four
blades.
34. The device of claim 30 wherein the hub is a 8'' square in plan
view.
35. The device of claim 30 wherein each blade has a height between
6'' and 7''.
36. The device of claim 30 wherein the leading face includes a
surface that is angled to direct molten metal in a partially upward
direction.
37. The device of claim 30 that further includes a circulation pump
positioned in the vessel.
38. The device of claim 30 wherein the vessel has two compartments.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of and claims priority to
U.S. application Ser. No. 10/827,941 filed Apr. 19, 2004, which is
a divisional application of and claims priority to U.S. patent
application Ser. No. 09/649,190, filed Aug. 28, 2000, now U.S. Pat.
No. 6,723,276.
FIELD OF THE INVENTION
[0002] The present invention relates to a device, called a scrap
melter, for submerging scrap metal in a molten metal bath. The
device preferably includes a drive source, an impeller and a drive
shaft. The device preferably draws molten metal downward in order
to submerge scrap placed on the surface of the bath.
BACKGROUND OF THE INVENTION
[0003] Scrap melter systems, such as the one shown schematically in
FIGS. 1 and 2, generally use two devices, a circulation pump and a
scrap melter. As shown in FIG. 1 the vessel V containing molten
metal bath B is preferably divided into two compartments.
Compartment 1 (called a pump well) houses circulation pump 2.
Compartment 3 (called a charge well) houses a scrap melter 10. The
circulating molten metal moves between compartment 1 and
compartment 3 and is preferably circulated throughout vessel V.
Scrap S is introduced into compartment 3 and is submerged by the
downward draw created by the impeller of scrap melter 10, which
pulls the scrap downward into the molten metal bath. The molten
metal bath is preferably maintained, at least partially, in a
remelting furnace having a heating chamber interconnected to a
melting chamber. Bath B is maintained at a temperature above the
melting point of the scrap metal in order to melt the scrap
metal.
[0004] A conventional scrap melter includes an impeller affixed to
a drive shaft, and a drive source for rotating the shaft and the
impeller. As stated above, the impeller draws molten metal and the
scrap metal downward into the molten metal bath in order to melt
the scrap. The circulation pump is preferably positioned in the
pump well and circulates the molten metal between the chambers in
order to maintain a relatively constant temperature within bath B.
Such a system, including a circulation pump and a scrap melter, is
disclosed in U.S. Pat. No. 4,598,899, issued Jul. 8, 1986 to
Cooper, the disclosure of which that is not inconsistent with this
disclosure is incorporated herein by reference. As defined herein,
the terms auger, rotor and impeller refer to the same general
structure, i.e., a device used in a scrap melter for displacing
molten metal.
[0005] Scrap melter impellers generally move molten metal radially
outward away from the impeller to create a downward draw above the
impeller. However, such impellers can create turbulence or flow
that may partially move into the path of the fluid entering the
impeller from above, in which case some scrap may not be
efficiently drawn into bath B where it can be melted and mixed,
thus decreasing the fluid flow to the impeller and decreasing the
efficiency of the scrap melting operation. In addition, the radial
turbulence may cause some fluid that has been expelled from the
impeller to be immediately recirculated through the impeller, thus
decreasing the flow of virgin fluid through the impeller. That
further decreases efficiency because it reduces the draw of molten
metal from above the impeller. As a result, in order to maintain a
desired volume of fluid flow through the impeller, the speed of the
impeller may be increased to overcome these effects. Increasing the
speed of the impeller, however, may cause excess vibration leading
to part failure, downtime and maintenance expenses.
[0006] Scrap melters have been developed to restrict radial flow
from the impeller to limit turbulence and produce more efficient
flow. One such assembly, disclosed in U.S. Pat. No. 4,930,986,
issued Jun. 5, 1990 to Cooper, the disclosure of which that is not
inconsistent with this disclosure is incorporated herein by
reference, includes an impeller positioned inside a drum, both of
which rotate as a single unit. One disadvantage to this assembly is
that pieces of scrap or dross can jam in it, which decreases its
efficiency. Other prior art devices are disclosed in U.S. Pat. Nos.
4,286,985, 3,984,234, 4,128,415 and 4,322,245.
SUMMARY OF THE INVENTION
[0007] The preferred embodiment of the present invention is a scrap
melter utilizing an open impeller to reduce jamming or clogging.
Thus, the invention can function efficiently in virtually any scrap
melting environment, handling particles of virtually any size that
are likely to be encountered in any such environment. An impeller
according to the invention functions by displacing molten metal to
create a downward draw. It provides the benefit of reducing the
problems associated with faster operating speeds (i.e., the
possible creation of a vortex and turbulence, and/or part failure,
greater downtime and higher maintenance costs). The way in which it
achieves these results is by (a) displacing more molten metal while
operating at the same speed as conventional impellers, and/or (b)
moving at least some of the molten metal in a downward or partially
downward direction.
[0008] An impeller according to the invention displaces more molten
metal by the use of (1) a larger area on the blade surfaces that
push against the molten metal as the impeller rotates, and/or (2)
surfaces that push against the metal at angles that displace a
relatively large amount of molten metal. One impeller according to
the invention preferably moves molten metal at least partially in
the downward direction, while another moves molten metal only in an
outward direction.
[0009] In one preferred embodiment the impeller is preferably a
four-bladed cross wherein each blade preferably includes an angled
surface that directs molten metal at least partially in the
downward direction. The impeller creates a draw that draws molten
metal and any solid scrap metal contained therein downward into the
molten metal bath. It also preferably provides at least some radial
or partially radial flow, and may include a surface or structure
specifically designed to generate radial or partially radial flow,
to assist in circulating molten metal within the bath.
[0010] In another preferred embodiment, the impeller is preferably
a four-bladed cross wherein each blade preferably includes a
vertical surface that directs molten metal radially outward away
from the impeller. The impeller creates a draw that draws molten
metal and any solid scrap metal contained therein downward into the
molten metal bath. It also assists in circulating molten metal
within the bath.
[0011] A scrap melter according to the invention can be operated at
lower speeds than conventional melters but still displace the same
amount of molten metal per impeller revolution. Alternatively, it
can be operated at the same speeds as, and displace more molten
than conventional scrap melters. A benefit of the lower speed is
that the scrap melter of the invention vibrates less and requires
less maintenance and fewer replacement parts.
[0012] A preferred melter according to the invention includes a
drive source, a drive shaft having a first end and a second end and
an impeller. The first end of the drive shaft is connected to the
drive source. An impeller according to the invention is connected
to the second end of the drive shaft. The drive source is
preferably a pneumatic or electric motor, but can be any device(s)
capable of rotating the impeller.
[0013] A scrap melter according to the invention may be used in a
scrap melter system comprising a scrap melter, a vessel containing
a molten metal bath and a circulation pump. Conventional pumps for
pumping molten metal that may be used as circulation pumps are
generally disclosed in U.S. Pat. No. 2,948,524 to Sweeney et al.,
U.S. Pat. No. 5,203,681 to Cooper entitled "Submersible Molten
Metal Pump," pending U.S. application Ser. No. 08/759,780, filed
Dec. 13, 1996, entitled Molten Metal Pump With a Flexible Coupling
and Cement-Free Metal-Transfer Conduit Connection, U.S. Patent No.
to Cooper entitled Impeller Bearing System for Molten Metal Pumps,
U.S. application Ser. No. 09/152,168, filed Sep. 11, 1998, entitled
Improved Gas Dispersion Device, U.S. Pat. No. 5,678,807 to Cooper
and U.S. Pat. No. 5,662,725 to Cooper, the disclosures of which are
incorporated herein by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Embodiments of the present invention will now be described
with reference to the drawings, wherein like designations denote
like elements, and:
[0015] FIG. 1 is a side view of a scrap melter system according to
the invention comprising a scrap melter, a vessel and an impeller
according to the invention.
[0016] FIG. 2 is a top view of the system shown in FIG. 1.
[0017] FIG. 3 is a perspective view of a preferred impeller
according to the invention.
[0018] FIG. 4 is perspective view of an alternate preferred
impeller according to the invention.
[0019] FIG. 5 shows an exploded, perspective view of an assembly
according to the invention, including a drive shaft, the impeller
of FIG. 3 and a nut.
[0020] FIG. 6 is a partial side view of the assembly shown in FIG.
5, showing the connected components.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] Referring now to the figures, where the purpose is for
describing a preferred embodiment of the invention and not for
limiting same, FIG. 1 shows a scrap melter 10 submerged in a molten
metal bath B. All of the components of scrap melter 10 exposed to
molten metal bath B are preferably formed from oxidation-resistant
graphite or other material suitable for use in molten metal.
[0022] A drive source 28 is connected to impeller 100 by any
structure suitable to transfer driving force from source 28 to
impeller 100. Drive source 28 is preferably an electric, pneumatic
or hydraulic motor although, as used herein, the term drive source
refers to any device or devices capable of rotating impeller
100.
[0023] A drive shaft 12 is preferably comprised of a motor drive
shaft (not shown) connected to an impeller drive shaft 40. The
motor drive shaft has a first end and a second end, the first end
being connected to motor 28 by any suitable means and which is
effectively the first end of drive shaft 12 in the preferred
embodiment. An impeller shaft 40 has a first end 42 (shown in FIG.
4) and a second end 44. The preferred structure for connecting the
motor drive shaft to impeller drive shaft 40 is a coupling (not
shown). The coupling preferably has a first coupling member and a
second coupling member. The first end 42 of impeller shaft 40 is
connected to the second end of the motor shaft, preferably by the
coupling, wherein the first end 42 of impeller shaft 40 is
connected to the second coupling member and the second end of the
motor drive shaft is connected to the first coupling member. The
motor drive shaft drives the coupling, which, in turn, drives
impeller drive shaft 40. Preferably, the coupling and first end 42
of the impeller shaft 40 are connected without the use of
connecting threads.
[0024] Impeller 100 is an open impeller. As used herein the term
open refers to an impeller that allows dross and scrap to pass
through it, as opposed to impellers such as the one shown in U.S.
Pat. No. 4,930,986, which does not allow for the passage of much
dross and scrap, because the particle size is often too great to
pass through the impeller. Preferred impeller 100 is best seen in
FIG. 3. Impeller 100 provides a greater surface area to move molten
metal than conventional impellers. Impeller 100 is preferably
imperforate, has two or more blades, is preferably formed of solid
graphite, is attached to and driven by shaft 12, by being attached
to shaft 40 in the preferred embodiment, and is preferably
positioned centrally about the axis of shaft 40. Impeller 100 may,
however, have a perforate structure (such as a bird-cage impeller,
the structure of which is known to those skilled in the art) or
partially perforate structure, and be formed of any material
suitable for use in a molten metal environment.
[0025] Impeller 100 most preferably has four blades 102 and is
shaped like a cross when viewed from the top. Impeller 100 includes
a central section, or hub, 104 that is the area defined by the
intersection between blades 102, when impeller 100 has three or
more blades. In the preferred embodiment, hub 104 is an
approximately 8'' square. A connective portion 106 is preferably a
nonthreaded, tapered bore extending through hub 104, but can be any
structure capable of connecting impeller 100 to drive shaft 12. The
preferred embodiment of impeller 100 also has a top surface 112, a
bottom surface 114, and a trailing face 116. The diameter of
connective portion 106 is approximately 5'' at upper surfacer 12
and tapers to approximately 4'' at lower surface 114 to form a
tapered bore as shown in FIGS. 3 and 5.
[0026] The height of surface 116, measured vertically, is
preferably between 6 and 7 inches. Each blade 102 preferably
extends approximately 10'' outward from hub 104, the overall
preferred length and width of impeller 100, including hub 104,
therefore being approximately 28''. A recess (not shown) may be
formed from top surface 112 to trailing surface 116.
[0027] Preferably, each blade 102 has the same configuration so
only one blade 102 shall be described. In the preferred embodiment,
blade 102 has a leading face 108. Face 108 is on the leading side
of blade 102 as it rotates (as shown impeller 100 is designed to
rotate in a clockwise direction). Face 108 includes an angled
portion 108A and a vertical lip 108B. Portion 108A directs molten
metal at least partly in the downward direction, toward the bottom
of vessel V, as shown in FIG. 1. Surface 108A may be substantially
planar or curved, or multi-faceted, such that, as impeller 100
turns, surface 108A directs molten metal partially in the downward
direction. Any surface or structure that functions to direct molten
metal downward or partially downward can be used, but it is
preferred that surface 108A is formed at a 30.degree.-60.degree.,
and most preferably a 45.degree. planar angle. Alternatively,
leading face 108 may itself be, or include a surface that is, (1)
vertical, (2) substantially vertical, or (3) angled to direct
molten metal in a partially upward direction, because the radial
displacement of molten metal alone will create a downward draw in
the space above impeller 100.
[0028] Impeller 300, shown in FIG. 4, is also an open impeller.
Preferred impeller 300 is best seen in FIG. 4. Impeller 300 also
provides a greater surface area to move molten metal than
conventional impellers. Impeller 300 is preferably imperforate, has
two or more blades, is preferably formed of solid graphite, is
attached to and driven by shaft 12, by being attached to shaft 40
in the preferred embodiment, and is preferably positioned centrally
about the axis of shaft 40. Impeller 100 may, however, have a
perforate structure (such as a bird-cage impeller, the structure of
which is known to those skilled in the art) or partially perforate
structure, and be formed of any material suitable for use in a
molten metal environment.
[0029] Impeller 300 most preferably has four blades 302. Impeller
300 includes a central section, or hub, 304 that is the area
defined by the intersection between blades 302, when impeller 300
has three or more blades. In the preferred embodiment, hub 304 is
an approximately 8'' square. A connective portion 306 is preferably
a nonthreaded, tapered bore extending through hub 304, but can be
any structure capable of connecting impeller 300 to drive shaft 12.
The preferred embodiment of impeller 300 also has a top surface
312, a bottom surface 314, and a trailing face 316. The diameter of
connective portion 306 is approximately 5'' at upper surface 312
and tapers to approximately 4'' at lower surface 314 to form a
tapered bore as shown in FIG. 4.
[0030] The height of surfaces 308, 316, measured vertically, is
preferably between 6 and 7 inches. Each blade 302 preferably
extends approximately 10'' outward from hub 304, the overall
preferred length and width of impeller 300, including hub 304,
therefore being approximately 28''. A recess (not shown) may be
formed from top surface 312 to trailing surface 316.
[0031] Preferably, each blade 302 has the same configuration so
only one blade 302 shall be described. In the preferred embodiment,
blade 102 has a leading face 308. Face 308 is on the leading side
of blade 302 as it rotates (as shown impeller 300 is designed to
rotate in a clockwise direction). Face 308 is vertical (as used
herein, the term vertical refers to any vertical or substantially
vertical surface) and directs molten metal outward away from
impeller 300. Face 308 may be substantially planar or curved, or
multi-faceted, such that, as impeller 300 turns, face 308 directs
molten metal outward. Any surface or structure that functions to
direct molten metal outward can be used, but it is preferred that
surface 308 is vertical and extends the full height of blade 308 so
that blade 308 has a square cross section. Alternatively, face 308
may itself be, or include a surface that is angled to direct molten
metal in a partially upward direction, because the radial
displacement of molten metal alone will create a downward draw in
the space above impeller 300.
[0032] As shown in FIGS. 5 and 6, second end 44 of impeller drive
shaft 40 preferably has a tapered section 44A that is received in
the tapered bore of the preferred embodiment of connecting portion
106. End 44 also preferably has a threaded section 44B that extends
below bottom surface 114 of impeller 100 when section 44A is
received in connecting portion 106. In this preferred embodiment, a
nut 200, that has a threaded opening 202, is screwed onto section
44B to retain impeller 100 on end 44 of rotor drive shaft 40. Nut
200 and section 44B preferably have 4''-41/2'' U.N.C. threads. Nut
200 is preferably a hex head nut having an overall diameter of
approximately 7''.
[0033] The purpose of tapered bore 106 is easy removal of end 44 of
shaft 40 from connective portion 106. Some prior art devices
utilize either a threaded bore and/or a right cylindrical bore,
i.e., a bore having the same diameter at the top and bottom to
connect the drive shaft to the impeller. The problem with such
structures is that during operation of the scrap melter molten
metal seeps between the end of the shaft and the bore in the
impeller. This leads to difficulty in removing the shaft from the
bore, and often the shaft must be chiseled out. The nonthreaded,
tapered bore 106 of the invention alleviates this problem. Although
only the preferred attachment of impeller 100 is shown, impeller
300 would preferably be attached to shaft 12 in the same manner as
described for impeller 100.
[0034] Preferred embodiments having now been described, variations
that do not depart from the spirit of the invention will occur to
others. The invention is thus not limited to the preferred
embodiment but is instead set forth in the following claims and
legal equivalents thereof, which are contemplated to cover any such
variations. Unless specifically stated in the claims, any of the
claimed inventions may include structures or devices other than
those specifically set forth in the claims.
* * * * *