Information
-
Patent Grant
-
6216924
-
Patent Number
6,216,924
-
Date Filed
Wednesday, December 23, 199825 years ago
-
Date Issued
Tuesday, April 17, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 222 594
- 222 606
- 222 607
- 164 306
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International Classifications
-
Abstract
A pressure tube includes a central tube section (10), an intake tube section (12) and a flared tube section (14). Flared tube section (14) includes a flange ring (54) with a shell (64) secured thereto. A contact ring (76) is received in an annular recess (82) of flange ring (54).
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention is directed to apparatus for making steel and, more particularly, apparatus for transferring molten steel from a ladle to a mold.
2. Description of the Prior Art
Various apparatus and processes have been developed for manufacturing steel. In steelmaking operations, it has been found that transferring molten metal to molds presents a step by which slag or other impurities are sometimes introduced. To improve steel quality, various processes for minimizing the introduction of impurities have been developed.
Such processes have included pressure casting processes wherein molten metal is transferred through a pressure tube and into a casting. Briefly, in the pressure casting process a ladle of molten metal is placed upright in an open pressure vessel. A refractory lined lid is then placed over the vessel. One end of the pressure tube is inserted through an opening in the lid and submerged in the molten metal. The opposite end of the tube is then connected to the mold. Air is pumped into the vessel to pressurize it. The air pressure on surface of the molten metal forces the metal upwardly through the pressure tube and into the mold. The metal enters the pressure tube through the submerged end of the tube and flows through the tube and into the mold. Since the molten metal flows from a location under the metal surface near the bottom of the ladle, the process tends to avoid the entrainment of slag in the molten metal and results in a high-quality casting.
In the prior art, pressure tubes have been made of various materials including alumina graphite, zirconia-alumina, high alumina, high alumina tar impregnated and coked, and muddite.
All of these tubes have the disadvantage that their preparation requires final assembly with a metal collar. The collar is bonded to the outside surface of the tube with a castable or mortar. The collar is located adjacent to one end of the pressure tube. The opposite end of the pressure tube is inserted through the lid opening and the pressure tube is passed through the lid opening until the collar engages the pressure vessel lid. The collar is located on the pressure tube such that the collar contacts the pressure vessel lid and one end of the tube is suspended in the molten metal during pressure casting.
To assemble the tube and collar, the metal collar is placed over one end of the refractory tube. The tube is secured to the collar by a mortar or castable that is placed between the inside wall of the collar and the outside wall of the refractory tube. After the tube is thus secured to the collar, a second layer of mortar is applied to the outer surface of the tube adjacent to the innermost end of the collar. This second layer of mortar is intended to prevent leakage of air between the collar and the tube while the tube is under pressurized conditions. Air leaks at this location are particularly undesirable because the air can then become entrained in the steel as it enters the mold. If air reaches the mold cavity, the mold is usually seriously damaged or destroyed. At a minimum, this results in degradation of the steel quality.
In the prior art, air leaks between the collar and the tube were sometimes caused by slippage between the collar and the tube that resulted in cracks in the mortar. Accordingly, various structures were employed to strengthen the engagement between the collar and the pressure tube. For example, in some cases circular grooves were cut in the external surface of the tube so that the castable or mortar could flow into these grooves to better engage the tube. In another example, the tube was provided with a circular groove and a steel retaining ring that was partially received in the groove extended from the tube to provide a circular flange around the tube. This also was found to improve the engagement between the collar and the tube.
Notwithstanding such improved designs, a persistent problem with the use of such collars has been that they potentially allowed passage of air through mortar cracks or seams between the pressure tube and the collar. This also created a potential for air to become entrained in the steel and carried into the mold. Moreover, the prior art process for assembling collars to the refractory tubes required substantial labor, time and space to complete. All of these requirements significantly added to the overall cost of the pressure casting process.
Thus, there was a need in the prior art for an improved design for pressure tubes that would further reduce the likelihood that a pathway between the collar and the refractory tube would develop and entrained air would enter the mold. Preferably, an improved design could also substantially reduce requirements for time, labor and space that were associated with the collar assembly process.
SUMMARY OF THE INVENTION
In accordance with the subject invention, a pressure cast tube includes a tube body that defines an internal passageway between an intake end and a mold end. The tube body has a larger diameter at longitudinal positions adjacent to the mold end than at longitudinal positions adjacent to the intake end. The tube body also incorporates a flange ring that is located adjacent to the mold end and that extends laterally outward from the rest of the tube body. A shell is secured to the flange ring and a contact ring is connected to the shell.
Preferably, the shell that is secured to the flange ring includes an annular band that is secured to the circumferential surface of the flange ring and an upper ring that is connected to one edge of the annular band. The contact ring is secured to an edge of the annular band that is opposite from the edge that is connected to the upper ring.
More preferably, the circumferential surface of the flange ring is separated from the lateral surface of the tube body by an upper annular surface and by a lower annular surface.
Other details, objectives and advantages of the subject invention will become apparent to those skilled in the art as description of a presently preferred embodiment proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the subject invention is shown in the accompanying drawings wherein:
FIG. 1
is an elevational section of a pressure tube in accordance with the subject invention;
FIG. 2
is an enlarged view of the top portion of the pressure tube shown in
FIG. 1
;
FIG. 3
is a top plan view of the complete pressure tube shown in
FIG. 1
;
FIG. 4
is an isometric view of the top portion of the pressure tube of
FIGS. 1-3
with portions thereof broken away to better disclose the structure thereof; and
FIG. 5
is an elevational section of the pressure tube of
FIGS. 1-4
mounted in a typical pressure vessel.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in
FIGS. 1-4
, a pressure tube as herein disclosed includes a tube body that has a central tube section or region
10
with an intake tube section or tapered region
12
on one end and a flared tube section or region
14
on the other end.
Central region
10
is in the general shape of a right circular cylinder with an outer circumferential surface
16
that is spaced at a substantially constant radius from a longitudinal center axis
18
. Central region
10
has a first or upper end or boundary
20
and a second or lower end
22
. Central region also includes an internal passageway
24
that is defined by an internal cylindrical surface
26
. Internal cylindrical surface
26
is located at a substantially constant radius from longitudinal axis
18
such that the wall thickness
28
between outer surface
16
and inner surface
26
is substantially constant over the longitudinal locations or positions of the central region
10
.
Tapered region
12
is an intake tube section that is defined between an intake end or distal end face
30
and a connection end face
32
. Tapered region
12
has an internal cylindrical surface
34
that defines an internal passageway
36
. Tapered region
12
is aligned on longitudinal axis
18
and is secured to central region
10
such that connection end face
32
is in opposition to lower end
22
. Internal passageway
36
is in communication with internal passageway
24
and internal surface
34
is located at substantially the same radius from center axis
18
as internal surface
26
. Also, at the longitudinal position on tapered region
12
that is adjacent to connection end face
32
, the outer surface
38
of tapered region
12
is located at substantially the same radius from longitudinal axis
18
as circumferential surface
16
so that wall thickness
40
of tapered region
12
is substantially the same as wall thickness
28
of central region
10
.
At locations along longitudinal axis
18
closer to distal end face
30
, outer surface
38
is located at a shorter radius from axis
18
such that tapered region
12
decreases in diameter along longitudinal axis
18
in the direction toward distal end face
30
. Internal surface
34
is located at a substantially constant radius throughout the length of tapered region
12
so that wall thickness
40
diminishes in the direction toward distal end face
30
. Preferably, central region
10
is secured to tapered region
12
by threaded member
42
.
Flared region
14
has a mold end face
44
. Flared region
14
joins central region
10
at boundary
20
. Flared region
14
is in longitudinal alignment with longitudinal axis
18
. Flared region
14
monolithically joins central region
10
at boundary
20
. Flared region
14
includes an internal cylindrical surface
48
and an outer circumferential surface
50
. Internal cylindrical surface
48
is at substantially constant radius from axis
18
at positions of flared region
14
along longitudinal axis
18
and defines an internal passageway
52
that is in communication with passageway
24
of central region
10
. A portion of flared region
14
in the region near mold end face
44
is comprised of a layer of alumina-graphite
52
a
. Layer
52
a
is hardened by boron carbide so that it is resistant to physical damage caused by impacts from the molds
52
b
(
FIG. 5
) as they are joined to the pressure tube or removed from the pressure tube.
In the portion of flared section
14
that is adjacent to boundary
20
, outer surface
50
is substantially the same radius from axis
18
as circumferential surface
16
of central region
10
. Also internal surface
48
is substantially the same radius from axis
18
as internal surface
26
of central region
10
. Accordingly, the wall thickness
52
b
of the portion of flared region
14
adjacent to boundary
20
is substantially the same as wall thickness
28
of central region
10
.
However, the lateral or radial location of outer surface
50
increases at longitudinal positions of flared region
14
in the direction from boundary
20
toward mold end face
44
such that wall thickness
52
b
of flared region
14
is greater at longitudinal positions that are closer to mold end face
44
in comparison to other longitudinal positions. Thus, flared region
14
generally defines a fustrum
53
wherein the base
53
a
of the fustrum is closer to the mold end face
44
than the top
53
b
of the fustrum.
Additionally, flared tube section
14
includes a flange ring
54
that is an integral portion of said flared tube section
14
. Flange ring
54
extends radially from outer surface
50
at a longitudinal position that is adjacent to the mold end face
44
of flared section
14
. Thus, flange ring
54
is located between mold end face
44
and the base
53
a
of the fustrum
53
.
In the preferred embodiment, flange ring
54
includes an outer circumferential surface such as radial surface
56
and two lateral sides
58
and
60
that extend between radial surface
56
and outer surface
50
of flared region
14
. Thus, radial surface
56
extends laterally beyond the base
53
a
of fustrum
53
to form a lateral side
58
therebetween.
The pressure tube herein disclosed further includes a steel shell
64
that is secured to flange ring
54
. Steel shell
64
includes an outer or annular band
66
that is secured to the boundary surface or radial surface
56
of flange ring
54
. Annular band
66
has an upper lateral or side edge
68
and a lower lateral or side edge
70
. Shell
64
further includes an upper ring
72
having an outer perimeter
74
. Upper ring
72
is connected to upper side edge
68
of annular band
66
along perimeter
74
.
A contact ring
76
has an outer perimeter edge or surface
78
and an inner annular edge or inner radial surface
80
. Inner radial surface
80
is located laterally outward from the surface
50
of tube section
14
and from base
53
a
of fustrum
53
. Radial face
58
includes an annular recess
82
that receives contact ring
76
. Annular recess
82
is defined by lateral surface
82
a
and a circular or radial edge
84
that opposes inner annular edge or inner radial surface
80
of contact ring
76
when contact ring
76
is received in annular recess
82
. The depth of annular recess
82
is determined by the longitudinal width of radial edge
84
and is substantially equal to the thickness of contact ring
76
such that the annular portion
85
a
of radial face
58
that is defined between circular edge
84
and base
53
a
of fustrum
53
is substantially coplanar with face
86
of contact ring
76
. Contact ring
76
is connected to the lower side edge
70
of annular band
66
at outer perimeter surface
78
.
Referring to
FIG. 5
, when the pressure tube is inserted through the lid
85
of the pressure vessel, contact ring
76
engages a steel flange
86
in the lid of the pressure vessel. This creates a pressure seal between contact ring
76
and lid
85
. In addition, steel flange
86
also engages the annular portion
85
a of radial face
58
that is defined between circular edge
84
and base
53
a
to provide a metal-to-refractory seal. This metal-to-refractory seal has been found to be tighter than the metal-to-metal seals known in the prior art.
Also in contrast to pressure tubes known in the prior art, the surfaces of flared region
14
that are exposed to the internal pressures in the pressure vessel define a monolithic body that has no seams or joints that could be penetrated or eroded by internal gases or vapors inside the pressure vessel. The pressure tube herein disclosed does not have a steel collar or steel clading that forms a steel-alumina-graphite interface that is exposed to the internal pressure of the pressure vessel. Instead, a continuous glaze-protected surface of alumina-graphite is presented to pressure conditions. This continuous surface has been found to be more resistant to oxidation so that the pressure tube herein disclosed is found to be more durable than prior art pressure tubes.
While a presently preferred embodiment of the subject invention has been shown and described herein, other various embodiments are also included within the scope of the following claims.
Claims
- 1. A pressure cast tube for conducting molten metal from a vessel to a casting, said tube comprising:a tube body having an intake end and a mold end with an outer surface between said intake end and said mold end, said tube body defining an internal passageway between said intake end and said mold end, said tube body having a cross-sectional dimension that is greater at longitudinal positions adjacent to said mold end than at longitudinal positions adjacent to said intake end, said tube body also forming a flange ring that is located at a longitudinal position adjacent to the mold end of said tube body, said flange ring defining a radial surface that is located laterally outwardly with respect to the outer surface of said tube body that is adjacent to said flange ring, said flange ring also defining at least one lateral side between the radial surface and the outer surface of the tube body that is adjacent to said flange ring, said lateral side including a radial edge with a first portion of the lateral side being located on one side of the radial edge and between the radial edge and the outer surface of the tube body that is adjacent to said flange ring, said lateral side also including a second portion that is located on the opposite side of the radial edge from the first portion and defining a recess, the first portion of the lateral side cooperating with the vessel to form a metal-to-refractory seal at times when the pressure cast tube is placed in the vessel, a shell that is secured to said tube body adjacent to said mold end, said shell including an outer band that is secured to the radial surface of the flange ring; and a contact ring that is connected to the outer band of said shell, said contact ring being received in the recess of the second portion of said lateral side.
- 2. The pressure cast tube of claim 1 wherein said flange ring defines a lateral surface and wherein said contact ring defines an annular surface that is substantially parallel to the lateral surface of said flange ring.
- 3. A pressure cast tube for conducting molten metal from a vessel to a casting, said tube comprising:a tube body having an intake end and a mold end and having a circumferential surface between said intake end and said mold end, said tube body defining an internal passageway between said intake end and said mold end, said tube body forming a laterally extending flange ring that is located on said tube body at a longitudinal position that is adjacent to the mold end of said tube body, said flange ring having an outer circumferential surface that extends laterally outwardly from the circumferential surface of said tube body that is adjacent to said flange ring, said flange ring also having at least one lateral side between the outer circumferential surface of the flange ring and the circumferential surface of the tube body that is adjacent to said flange ring, said lateral side including a radial edge with a first portion of the lateral side being located on one side of the radial edge and between the radial edge and the circumferential surface of the tube body, said lateral side also having a second portion that is located on the opposite side of the radial edge from the first portion and that defines a recess, the first portion of the lateral side cooperating with the vessel to form a metal-to-refractory seal at times when the pressure cast tube is placed in the vessel; an annular band that is secured to the circumferential surface of the flange ring, said annular band having an upper edge and a lower edge; an upper ring having an outer perimeter that is connected to the upper edge of said annular band; and a contact ring having an outer perimeter and having an inner radial edge, the outer perimeter of said contact ring being connected to said annular band, said contact ring being received in the recess of the second portion of said lateral side, said contact ring contacting the vessel at times when the pressure cast tube is placed in the vessel.
- 4. A pressure cast tube for conducting molten metal from a vessel vertically upward to a casting; said tube comprising:a central tube section that is substantially in the shape of a right circular cylinder said central tube section having a first end and also having a second end that is oppositely disposed from said first end; an intake tube section that is secured to the first end of the central tube section; and a flared tube section having a tube end and an oppositely disposed mold end with said tube end being connected to the second end of said central tube section, said flared tube having an outer surface between said tube end and said mold end, with said outer surface having a larger diameter at longitudinal positions that are closer to the mold end in comparison to the diameter at other longitudinal positions that are closer to the tube end, said flared tube section also forming a flange ring having an outer circumferential surface and at least one lateral side that extends radially between the outer circumferential surface of the flange ring and the outer surface of said flared section that is adjacent to said flange ring, said flange ring being located longitudinally adjacent to the mold end of said flared tube section, said lateral side including a radial edge with a first portion of the lateral side being located on one side of the radial edge and between the radial edge and the outer surface of the flared section that is adjacent to said flange ring, said lateral side also having a second portion that is located on the opposite side of the radial edge from the first portion and that defines a recess, the first portion of the lateral side cooperating with the vessel to form a metal-to-refractory seal at times when the pressure cast tube is placed in the vessel; and a shell that is secured to the flange ring, said shell including an annular band that is secured to the outer circumferential surface of the flange ring, said annular band having an upper edge and a lower edge, said shell further including an upper ring having an outer perimeter that is connected to the upper edge of said annular band, and said shell also having a contact ring that has an outer perimeter that is connected to the lower edge of said annular band, said contact ring also having an inner radial edge that opposes the radial edge of the lateral side and that is received in the recess of the second portion of the lateral side, said contact ring contacting the vessel at times when the pressure tube is placed in the vessel.
- 5. The pressure tube of claim 4 wherein the flared tube section is comprised of alumina graphite and wherein the mold end of said flared tube section is further comprised of boron carbide.
- 6. The pressure tube of claim 4 wherein said pressure tube is comprised of alumina graphite.
- 7. A pressure cast tube for conveying molten metal from a pressurized vessel vertically upward to a casting, said tube comprising:a central tube section that is substantially a right circular cylinder, said central tube section having an end face and also having an end boundary that is oppositely disposed from said end face, said central tube section also defining an internal passageway between said end face and said end boundary; an intake tube section that has a distal end face and a connection end face, said intake tube section being secured to said central tube section with said connection end face opposing the end face of said central tube section, said intake tube section defining an internal passageway between said distal end face and said connection end face with the internal passageway of said intake tube section being in communication with the internal passageway of said central tube section; and a flared tube section having a mold end face and a connection end boundary with an outer surface between said mold end face and said connection end boundary, said flared tube section being secured to said central tube section with said connection end boundary opposing the end boundary of said central tube section, said flared tube section defining an internal passageway between said mold end face and said connection end boundary with the internal passageway of said flared tube section being in communication with the internal passageway of said central tube section, the outer surface of said flared tube section having a circumference at a given longitudinal position that is greater than the circumference at longitudinal positions between the given position and the connector end boundary, said flared tube section also including a flange ring that is located at a longitudinal position that is adjacent to the mold end of said flared tube section said flange ring having a circumferential surface that is separated from the outer surface of said flared tube section that is adjacent to said flange ring by an upper lateral side and by a lower lateral side, said lower lateral side including a radial edge with a first portion of the lower lateral side being located on one side of the radial edge and also being located between the radial edge and the outer surface of the flared tube section that is adjacent to said flange ring, said lateral side also having a second portion that is located on the opposite side of the radial edge from the first portion and that defines a recess, the first portion of the lateral side cooperating with the vessel to form a metal-to-refractory seal at times when the pressure cast tube is placed in the vessel; and a collar that is secured to the flange ring, said collar including an annular band that is secured to the circumferential surface of the flange ring, said collar further including a contact ring that is connected to said annular band, said contact ring being received in the recess of the second portion of said lateral side, said contact ring contacting the vessel at times when the pressure cast tube is placed in the vessel.
- 8. A pressure cast tube for conveying molten metal from a vessel to a casting, said tube comprising:a tube body having an intake end and a mold end, said tube body defining an internal passageway between said intake end and said mold end, a portion of said tube body adjacent said mold end defining a fustrum with the base of said fustrum closer to said mold end than the top of said fustrum, said tube body further including a flange ring that is located between the mold end of said tube body and the base of said fustrum, said flange ring having a circumferential surface that extends laterally beyond the base of said fustrum to form a lateral face between said base and the circumferential surface of said flange ring, the lateral face of said flange ring including a radial edge with a first portion of the lateral face being located on one side of the radial edge and between the radial edge and the base of said fustrum, said lateral face further including a second portion that is located on the opposite side of the radial edge from the first portion and defining a recess, the first portion of the lateral face cooperating with the vessel to form a metal-to-refractory seal at times when the pressure cast tube is placed in the vessel; a contact ring that is received in the recess of the second portion of said lateral face and that is secured to the lateral face of said flange ring, said contact ring having an outer perimeter and at least one planar face, the thickness of the contact ring being substantially equal to the depth of the recess of said lateral face, such that the first portion of the lateral face is substantially coplanar with the planar face of said contact ring; and a shell that is secured to the circumferential surface of said flange ring, said shell also being secured to the outer perimeter of said contact ring with said contact ring contacting the vessel at times when the pressure tube is placed in the vessel.
- 9. The pressure cast tube of claim 8 wherein said tube body defines an outer surface between the intake end and the base of said fustrum and wherein said contact ring defines an inner radial edge that is located laterally outwardly from the outer surface of said tube body and wherein the lateral face of said flange ring defines an annular recess and wherein the contact ring is received in the annular recess.
- 10. The pressure cast tube of claim 9 wherein the radially inner boundary of the annular recess is defined by a circular edge that opposes the inner radial edge of the contact ring when the contact ring is received in the annular recess.
- 11. The pressure cast tube of claim 10 wherein the portion of the lateral face of said flange ring that is defined between the circular edge of the annular recess and the base of said fustrum is substantially coplanor with the face of said contact ring when the contact ring is received in the annular recess.
US Referenced Citations (6)