NZ759351B2 - Dynamic mold shape control for direct chill casting - Google Patents
Dynamic mold shape control for direct chill casting Download PDFInfo
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- NZ759351B2 NZ759351B2 NZ759351A NZ75935118A NZ759351B2 NZ 759351 B2 NZ759351 B2 NZ 759351B2 NZ 759351 A NZ759351 A NZ 759351A NZ 75935118 A NZ75935118 A NZ 75935118A NZ 759351 B2 NZ759351 B2 NZ 759351B2
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- side wall
- side walls
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- casting
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Abstract
Provided herein is a system, apparatus, and method for continuous casting of metal, and more particularly, to a mechanism for controlling the shape of a direct chill casting mold to dynamically control a profile of an ingot cast from the mold during the casting process. Embodiments may provide an apparatus for casting material including: first and second opposing side walls; first and second end walls extending between the first and second side walls, where the first and second opposing side walls and the first and second opposing end walls form a generally rectangular shaped mold cavity. At least one of the first and second opposing side walls may include two or more contact regions, where each of the two or more contact regions may be configured to be displaced relative to a straight line along the side wall. The system of example embodiments produces a cast ingot with a uniform profile over its length and eliminates swelling to reduce waste. paratus for casting material including: first and second opposing side walls; first and second end walls extending between the first and second side walls, where the first and second opposing side walls and the first and second opposing end walls form a generally rectangular shaped mold cavity. At least one of the first and second opposing side walls may include two or more contact regions, where each of the two or more contact regions may be configured to be displaced relative to a straight line along the side wall. The system of example embodiments produces a cast ingot with a uniform profile over its length and eliminates swelling to reduce waste.
Description
DYNAMIC MOLD SHAPE CONTROL FOR DIRECT CHILL CASTING
TECHNOLOGICAL FIELD
[0001] The t invention relates to a system, apparatus, and method for continuous
casting of metal, and more particularly, to a mechanism for controlling the shape of a
direct chill casting mold to dynamically control a profile of an ingot cast from the mold
during the casting process.
BACKGROUND
Metal products may be formed in a variety of ways; however numerous
forming methods first e an ingot, billet, or other cast part that can serve as the raw
material from which a metal end product can be manufactured, such as through rolling or
machining, for example. One method of manufacturing an ingot or billet is through a
semi-continuous casting s known as direct chill casting, whereby a vertically
oriented mold cavity is situated above a platform that translates vertically down a casting
pit. A ng block may be situated on the platform and form a bottom of the mold cavity,
at least initially, to begin the casting process. Molten metal is poured into the mold cavity
pon the molten metal cools, typically using a cooling fluid. The platform with the
starting block thereon may d into the casting pit at a predefined speed to allow the
metal exiting the mold cavity and descending with the starting block to solidify. The
platform continues to be lowered as more molten metal enters the mold cavity, and solid
metal exits the mold cavity. This uous casting process allows metal ingots and
billets to be formed according to the profile of the mold cavity and having a length limited
only by the casting pit depth and the hydraulically actuated platform moving therein.
BRIEF SUMMARY
The present invention relates to a system, tus, and method for continuous
casting of metal, and more particularly, to a ism for controlling the shape of a
direct chill casting mold to cally control a profile of an ingot cast from the mold
during the casting s. Embodiments may provide an apparatus for casting material
including: first and second opposing side walls; first and second end walls extending
between the first and second side walls, where the first and second opposing side walls
and the first and second opposing end walls form a generally rectangular shaped mold
cavity. At least one of the first and second opposing side walls may include two or more
contact regions, where each of the two or more contact s may be configured to be
ced relative to a straight line between a first end of the at least one of the first and
second ng side walls and a second end of the at least one first and second opposing
side walls in se to receiving a respective force applied externally from the mold
cavity. The respective displacement at a first of the two or more t regions may be
different from a displacement at a second of the two or more contact regions, and a
tive force at each of the two or more contact regions may change the curvature of
the at least one of the first and second opposing side walls.
[0004] According to some ments, the respective force at the first of the two or
more contact regions may include a force in a first direction, where the respective force at
the second of the two or more contact regions may include a force in a second direction,
opposite the first direction. The respective force at the first of the two or more contact
regions may include a force of a first magnitude in a first direction, where the respective
force at the second of the two or more contact regions may include a force of a second
magnitude in the first direction, the second magnitude being different from the first
magnitude. The first and second opposing side walls may include an inner g surface
and an outer surface. Each of the first and second opposing side walls may further include
a le bladder disposed along the outer surface, where a cooling fluid chamber is
defined between each respective opposing side wall and the respective flexible bladder.
The casting surface of each of the first and second opposing side walls may include a
plurality of orifices in fluid ication with a respective fluid chamber. A baffle may
be disposed between a cooling fluid chamber and the respective side wall, where the baffle
includes a plurality of flow-restricting orifices. The plurality of es in each of the first
and second opposing side walls may be configured to direct cooling fluid from the
respective cooling fluid channel toward a cast material as the cast material advances past
the casting surfaces of the first and second opposing side walls.
The first and second opposing side walls and the first and second opposing end
walls of example embodiments may cooperate to define a mold cavity having a shape
defined by the opposing side walls and end walls. Example embodiments of an apparatus
may e: first means for applying a first force to a first of the two or more contact
regions; and second means for applying a second force to a second of the two or more
contact regions. The first means and the second means may be controlled by a single
controller to change the shape of the mold cavity according to one or more properties of
the al to be cast. The first means and second means may be configured to change the
shape of the mold cavity as the material is cast based on one or more of a cast material
alloy, a temperature of the cast material g the mold cavity, a temperature profile of
the cast material, or a shape of the cast material exiting the mold cavity.
[0006] Embodiments of an apparatus provided herein may e a controller, where
the displacement of the first contact region and the cement of the second contact
region are performed in response to at least one of an unexpected slowing of liquid into
the mold cavity or feedback from an or applying a respective force to one or both of
the first contact region and the second contact region. Embodiments may include two or
more fixed position members, where the two or more fixed position s may be
configured to resist movement of the first and second opposing side walls in response to a
respective force applied at one or more of the two or more contact regions. The first and
second opposing side walls may each include an upper portion and a lower portion. The
upper portion of the at least one of the first and second opposing side walls may be
displaced proximate the first contact region a first distance relative to the straight line
between the first end of the at least one of the first and second opposing side walls and the
second end of the at least one first and second opposing side walls. The lower portion of
the at least one of the first and second ng side walls may be displaced proximate the
first contact region a second distance relative to the straight line between the first end of
the at least one of the first and second opposing side walls and the second end of the at
least one first and second opposing sidewalls, thereby defining a taper between an upper
portion of the mold cavity and a lower portion of the mold cavity.
ments described herein may provide a system for casting metal. The
system may include: a controller; a mold including a first side wall, a second side wall
opposite the first side wall, a first end wall, and a second end wall opposing the first end
wall. The first side wall, second side wall, first end wall, and second end wall may
ate to define a mold cavity having a mold cavity profile. The system may include a
first force receiving element of the first side wall located opposite the mold cavity, where
a first force d to the first force receiving element may be controlled by the controller
and cause a first displacement of the first side wall at the first force receiving t. A
second force receiving element of the first side wall may be located opposite the mold
cavity, where a second force applied to the second force receiving element may be
lled by the controller and causes a displacement of the first side wall at the second
force receiving element. The first displacement may be different than the second
cement. The controller may be configured to adjust the first displacement of the first
force receiving element and the second displacement of the second force receiving
element during a casting process using the mold. The controller may adjust the first
displacement and the second cement in response to at least one of a property of the
metal being cast or a profile of the metal exiting the mold.
According to some embodiments, the first side wall and the second side wall of
the mold may each include a plurality of orifices for directing cooling fluid along metal
exiting the mold during the casting process. A cooling fluid channel may be defined along
the first side wall outside of the mold cavity, where the cooling fluid channel may be
defined between the first side wall and a flexible bladder. The first force and the second
force may be configured to be d to the first force ing element and the second
force receiving t in te directions. Each of the first side wall and the second
side wall may define therein a respective cooling fluid channel and a plurality of cooling
fluid orifices. The system may include a g fluid supply, where the cooling fluid
supply may be configured to provide cooling fluid to each of the respective cooling fluid
channels to be sprayed through the plurality of orifices toward a cast material exiting the
mold cavity at different angles.
Embodiments described herein may provide a component of a mold. The
component may have a body extending along a length d between a first end wall and
a second end wall; an inner face defining a portion of a mold cavity and ing from
the first end wall to the second end wall; and an outer e opposite the inner face,
where the outer surface is configured to receive a first force and a second force. The first
end wall and the second end wall may be substantially stationary, where the component is
configured to be displaced from a first shape between the first end wall and the second end
wall to a second shape between the first end wall and the second end wall in response to
application of the first force and the second force, where the first force and the second
force are different.
Embodiments may provide a wall of a direct chill casting mold that includes: a
longitudinally extending body extending along a length n a first end and a second
end; an inner face defining a portion of a mold cavity and extending from proximate the
first end to proximate the second end, where a first set of orifices and a second set of
orifices are defined in the wall proximate the inner face; an outer face opposite the inner
face; a first fluid chamber disposed proximate the outer surface; and a second fluid
chamber disposed proximate the outer surface, wherein the first fluid chamber is in fluid
communication with the first set of orifices and the second fluid chamber is in fluid
ication with the second set of orifices. According to some embodiments, the inner
face may be configured to be ced along an axis substantially orthogonal to the inner
face in response to receiving a force along the axis applied to the outer surface. The first
set of orifices may include a set of orifices arranged ate the inner face of the
longitudinally extending body and the first set of orifices may extend along the
longitudinally extending body. The second set of es may include a set of orifices
arranged proximate the inner face of the longitudinally extending body and the second set
of es may extend along the longitudinally ing body.
[0011] According to some embodiments, the wall of the direct chill casting mold may
include a first set of fasteners, a second set of fasteners, and a third set of fasteners, where
each of the first, second, and third set of ers extend longitudinally along the outer
surface. The first fluid chamber may be disposed between the first set of fasteners and the
second set of fasteners, and the second fluid chamber may be disposed between the second
set of fasteners and the third set of fasteners. The first fluid chamber and the second fluid
chamber may extend along the longitudinally extending body on the outer surface, where
the outer surface of the side wall defines at least one wall of the first fluid chamber and the
second fluid chamber. The first fluid chamber and the second fluid r may be
bounded on one side by the outer surface of the side wall and bounded opposite the outer
e of the side wall by a flexible membrane.
The wall of a direct chill casting mold of example ments may include a
force receiving member, where the force receiving member may be attached to the outer
surface of the udinally extending body and is attached to the outer surface of the
longitudinally extending body by a first subset of at least two of the first set of fasteners,
the second set of fasteners, and the third set of fasteners. The force receiving member may
be repositionable along the longitudinally extending sets of fasteners using a second subset
of at least two of the first set of fasteners, the second set of fasteners, and the third set of
fasteners, where the second subset is different from the first subset. The first fluid chamber
may be in fluid communication with the first set of orifices through a passaged defined
within the side wall. The inner face of the side wall may include a graphite material, where
the graphite material may be configured to flex in congruence with the wall of the direct
chill casting mold.
BRIEF PTION OF THE DRAWINGS
Having thus described the ion in general terms, reference will now be
made to the accompanying drawings, which are not necessarily drawn to scale, and
wherein:
[0014] illustrates an example embodiment of a direct chill casting mold
according to the prior art;
illustrates an ingot formed through direct chill casting according to the
prior art;
illustrates a top view of a direct chill casting mold having sides with an
able curvature profile according to an example embodiment of the present invention;
illustrates a bottom view of a direct chill casting mold having sides with
an able curvature profile according to an example embodiment of the present
invention;
depicts a side wall assembly of a direct chill casting mold according to
an e embodiment of the present ion;
depicts another view of a side wall assembly of a direct chill casting
mold according to an example ment of the present invention;
illustrates a component view of a side wall and force receiving member
of a side wall ly of a direct chill casting mold in a straight configuration according
to an example embodiment of the present invention;
illustrates a view of the rear face of a portion of a side wall assembly of
a direct chill casting mold ing to an example embodiment of the present invention;
illustrates the component view of a side wall and a force receiving
member of a side wall assembly of a direct chill casting mold in a curved configuration
according to an example ment of the present invention;
depicts an end of a portion of a side wall assembly of a direct chill
mold according to an example embodiment of the present invention;
illustrates a mechanism for force distribution along a side wall of a
side wall assembly of a direct chill mold according to an example embodiment of the
present ion;
illustrates a cut-away view of a side wall of a direct chill mold
according to an example embodiment of the t invention;
illustrates a profile view of a mold wall of a direct chill mold including
an inner casting surface according to an example embodiment of the present invention;
illustrates a top view of a direct chill mold having adjustable side walls
according to an example embodiment of the present invention;
rates a top view of a direct chill mold having adjustable side walls
according to another example embodiment of the present ion;
[0029] depicts a mold frame assembly ing a plurality of direct chill
molds according to an example embodiment of the present invention; and
illustrates two nt side wall assemblies of adjacent direct chill
mold assemblies according to an example embodiment of the present invention.
DETAILED DESCRIPTION
Exemplary embodiments of the present invention now will be described more
fully after with reference to the accompanying drawings, in which some, but not all
ments of the ion are shown. Indeed, the ion may be ed in many
different forms and should not be construed as limited to the embodiments set forth herein;
, these embodiments are provided so that this disclosure will satisfy applicable legal
requirements. Like numbers refer to like elements throughout.
Embodiments of the present invention generally relate to the design of a direct
chill casting mold to facilitate a more consistent ingot profile. Vertical direct chill casting
is a process used to produce ingots or billets that may have large cross ns for use in a
variety of manufacturing applications. The process of vertical direct chill casting begins
with a horizontal table containing one or more vertically-oriented mold cavities disposed
therein. Each of the mold cavities is initially closed at the bottom with a ng block or
starting plug to seal the bottom of the mold cavity. Molten metal is introduced to each
mold cavity through a metal distribution system to fill the mold cavities. As the molten
metal ate the bottom of the mold, adjacent to the starting block solidifies, the
starting block is moved vertically downward along a linear path. The movement of the
starting block may be caused by a hydraulically-lowered platform to which the starting
block is attached. The movement of the starting block vertically downward draws the
solidified metal from the mold cavity while additional molten metal is introduced into the
mold cavities. Once started, this process moves at a relatively steady-state for a semicontinuous
casting process that forms a metal ingot having a profile defined by the mold
cavity, and a height defined by the depth to which the platform and starting block are
moved.
During the casting s, the mold itself is cooled to encourage solidification
of the metal prior to the metal exiting the mold cavity as the starting block is ed
downwardly, and a cooling fluid is uced to the surface of the metal proximate the
exit of the mold cavity as the metal is cast to draw heat from the cast metal ingot and to
solidify the molten metal within the now-solidified shell of the ingot. As the starting block
is advanced downward, the cooling fluid may be sprayed directly on the ingot to cool the
surface and to draw heat from within the core of the ingot.
The direct chill casting process enables ingots to be cast of a wide variety of
sizes and lengths, along with g profile shapes. While circular billet and rectangular
ingot are most , other profile shapes are possible. Circular profile billets benefit
from a uniform shape, where the distance from the al surface around the billet to the
core is lent around the perimeter. However, rectangular ingots lack this uniformity
of surface-to-core depth and thus have additional challenges to consider during the direct
chill casting s.
[0035] A direct chill casting mold to produce an ingot with a rectangular profile does
not have a perfectly rectangular mold cavity due to the deformation of the ingot as it cools
after leaving the mold cavity. The portion of the ingot exiting the mold cavity as the
platform and the starting block descend retains a molten or at least partially molten core
inside the solidified shell. As the core cools and solidifies, the external profile of the ingot
s such that the mold cavity profile, while it defines the shape of the final, cooled
ingot, does not have a shape or profile that is identical to the final, cooled ingot.
is an example embodiment of a conventional direct chill casting mold
100 which would be received within a table or frame assembly of a direct chill casting
system. As shown, the mold 100 includes first 110 and second 120 opposing side walls
extending between first 130 and second 140 end walls of the mold cavity. The first and
second opposing side walls 110, 120 and the first and second end walls 130, 140, combine
to form the mold cavity 150 having a generally rectangular profile. The first and second
opposing side walls 110, 120, have an arcuate shape, or at least some degree of curvature
to the wall profile. This shape enables the cast ingot to have substantially flat ng
sides during a steady-state casting operation of the direct chill g process. The end
walls 130 and 140 may also have a specified shape, which may include a curvature, a
series of flat sides arranged in an arcuate shape, a compound curvature, or a straight side,
for e. The "steady-state" portion of the casting process, as described herein, is the
portion of the casting process after the l start-up phase or start up casting phase and
before the end of the casting process or ending casting phase. Steady-state casting occurs
when the ature e in the portion of the ingot exiting the mold cavity remains
constant or near constant. Different g control parameters may be desired at each
phase of the casting from starting phase to -state phase to ending phase based on the
type of material being cast.
While direct chill casting molds have been designed and developed to generate
an ingot having substantially flat sides on its rectangular profile for the ingot portion
produced during a steady-state portion of the casting process, the start-up process of direct
chill casting includes challenges that distinguish the start-up casting phase s and the
initial portion of the ingot formed during the start-up casting phase s from the
steady-state phase of the casting process and the portion of the ingot formed during
steady-state casting.
During the start-up phase of direct chill casting, high thermal gradients induce
thermal stresses that cause deformation of the ingot in manners that are distinct from those
experienced during the steady-state phase of casting. Due to the changes in thermal
gradients and stresses experienced in the start-up phase versus the steady-state phase of
g, a constant-profile mold cavity results in a non-uniform profile of the ingot portion
cast during the start-up phase, also known as the butt, and the ingot cast during the steadystate
casting phase. As the portion produced during steady-state casting forms the majority
of the ingot, the mold profile may be ed such that the opposed sides and ends of an
ingot are substantially flat. This may result in a butt of the ingot formed during the start-up
phase lacking ntially flat sides, as illustrated in the cast ingot section of The illustrated embodiment of depicts a basic cross-section of an ingot mold
during the casting process. As illustrated, the molten metal 161 is ed within the
cavity of the mold, between mold side walls 110 and 120, where the molten metal
transitions to solid metal proximate the sump indicated by dashed line 163. The starting
block 157 of the illustrated position has y descended with the platform 159 in the
direction of arrow 162, and the casting is presently in the steady-state phase, with the sides
165 of the ingot 160 being substantially flat. The n of the ingot 160 produced during
the start-up phase is shown adjacent to the starting block 157 with a profile that is swollen
170 with respect to the desirable flat sides 175 of the steady-state casting phase.
The deformation of the ingot portion produced during the start-up phase 170
may not be usable depending upon the end-use of the ingot, such that the portion of the
ingot formed during the start-up period may be sacrificial (i.e., cut from the ingot and
repurposed/re-cast). This sacrificial butt portion of the ingot may be substantial in size,
particularly in direct chill g molds that have relatively large es, and while the
butt may be re-cast so the material is not lost, the lost time, reheating/re-melting costs and
labor associated with the lost portion of the ingot, and the d maximum size potential
of an ingot result in losses in efficiency of the direct chill casting process. Similar issues
may exist at the end of a casting in g the "head" of the ingot or billet, where casting
ceases to be steady-state and may require specific control parameters to maximize the
useable portion of the ingot and reducing waste.
Certain embodiments of the t invention e a direct chill casting
mold that has flexible opposing side walls that may be dynamically moved during the
casting process to eliminate the butt swell of conventional direct chill ingot casting molds
to reduce waste and to improve the efficiency with which ingots are cast. Direct chill
g molds as described herein may include an opposed pair of casting surfaces on side
walls of the mold that are flexible allowing them to change shape while the mold is casting
an ingot. Each of the opposed side walls may include two or more contact portions or
force receiving elements, each configured to receive a force that causes the opposed side
walls of the mold to move dynamically and change shape during the casting s. The
forces applied to the two or more contact regions may be independent and may include
forces in opposing directions, as described further below. The contact regions may
optionally be repositionable along the length of the opposing side walls to enable greater
control over the shape of the side wall resulting from the forces applied.
illustrates a top-view of a direct chill casting mold assembly 200
according to an example embodiment of the present invention. As shown, the mold
assembly 200 es first and second opposing side wall assemblies 210, 220, and first
and second end wall assemblies 230, 240. Each of the opposing side wall assemblies 210,
220 include a side wall of the mold cavity 250 that ate with end walls of end wall
assemblies 230 and 240 to form the profile of the mold cavity which is the shape of the
perimeter of the mold cavity.
illustrates a view of the bottom plates of the mold assembly 200,
omitting the side wall lies and top plates of the mold assembly visible in for
ease of understanding. As shown, the bottom plates 212 and 222 of the opposing side wall
assemblies 210 and 220 include a curvature 214 and 224 in the edge facing the mold
cavity 250. This curvature provides an opening at the bottom of the mold assembly 200
that is at least as large as the side walls and end walls of the mold cavity 250 may provide.
While the side walls of the mold ly 200 may define a curvature that is less than that
of the respective bottom plate 212, 222, the curvature of the respective side walls may not
be greater than the curvature 214, 224 of the bottom plates 212, 222 of the side wall
assemblies 210, 220.
[0043] As noted above, the opposing side walls of example embodiments described
herein may include a profile that is cally adjustable from between two or more
curvature profiles. The adjustment of the opposing side wall curvature may enable an
ingot butt or billet butt produced at the start-up of the casting process to be produced
without ng or other dimensional or physical attributes that render the butt
unsatisfactory for the intended purpose of the billet or ingot being cast. e
embodiments described herein allow near infinite size optimization from one mold in a
given casting pit.
illustrates one of the pair of opposing side wall assemblies 210
including a top plate 216, an actuation plate 218, and a bottom plate 212. The bottom plate
includes curvature 214 as described above with respect to The side wall 211 is
illustrated in a substantially straight, un-bent configuration. Also visible is fluid conduit
block 260 configured to allow cooling fluid to flow through channels disposed behind the
side wall 211, as described and illustrated below. The side wall may include a taper from
the top to the bottom, narrowing the opening 250. While any degree of taper may be used,
a desirable range may be on the order of one half of a degree of taper to three degrees of
taper from the top edge of the side wall 211 to the bottom edge of the side wall. The fluid
conduit block 260 may e a fluid flow path to adapt the fluid flow from an inlet of the
fluid conduit block to one or more fluid chambers of the side wall assembly 210. The fluid
conduit block 260 may ally include one or more valves to control the flow of fluid
through the fluid conduit block 260 to the one or more fluid chambers of the side wall
assembly 210. The fluid t block 260 may optionally include one or more filter
elements to filter fluid as it passes through the fluid conduit block. Further, the fluid
conduit block 260 may optionally regulate pressure of the g fluid.
The side wall 211 of example embodiments may be made of a material that is
strong, but flexible to facilitate bending of the mold wall as described in greater detail
below. For e, aluminum may be used, and in particular, 6061-T651 may be selected
due to the strength-to-flexibility ratio and corrosion resistance. um with a T651
treatment is solution heat treated, stress-relieved, and cially aged which enhances
properties ble in embodiments of the present application. Casting of molten
aluminum may influence the metal composition, though embodiments described herein
may lose temper only in the surface of the mold walls as the cooling mechanisms
described below will help maintain a lower temperature in the mold walls and thus the
temper and strength of the material used for the mold walls will be more consistently
maintained. A-0 temper (annealed) may be used due to the distance from the g
surface to the water r being low such that the temperature gradient across the mold
wall material may be high.
Cooling fluid pressure within the fluid rs sed further below may
be in a range about 0 psi s per square inch) to about 45 psi, and desirably between
about 2 psi and 15 psi. On the face of side wall 211 there are a plurality of orifices 262
arranged at a position on the side wall proximate the top of the mold cavity for directing
lubricating fluid from the side wall 211 toward the mold cavity. A second set of orifices
may also be ed as shown at 264 as will be illustrated below. The first set of orifices
262 may be configured to direct a lubricating fluid toward the mold cavity to lubricate the
casting surface (i.e., the surface surrounding the mold cavity along which the molten metal
is solidified) of the side wall 211 during casting. The casting surface is the portion of the
side wall that is in contact with the cast al, or facing the cast material and separated
there from by the lubricating fluid. The casting surface may include a friction-reducing
material, such as a g or an insert, to supplement the lubricating properties of the
lubricating fluid, such as a graphite material. The casting surface may be coated with a
low-friction coating or may receive a low-friction material insert therein, such as a
graphite insert, which may be replaceable and may not require lubricant.
An inner casting surface of graphite or another porous material may be used to
function as a oir or sponge for grease or lubricant to distribute the grease or lubricant
during the casting process, and potentially for multiple casts. This may enable grease or
lubricant to be applied once before a cast or possible once before a sequence of casts. The
inner casting surface may be flexible to enable the inner casting surface to flex with the
wall of the mold to create the desired bore profile and resultant casting profile. The
graphite or other inner g e material may be secured to the wall of the mold
using adhesive or mechanical means, such as shrink fitting, fasteners, dovetail, or other
grooves, for example. The cross section of the inner casting surface al may be
constant or vary along the length or height of the material. For example, the material may
be wider proximate the top of the inner casting surface and narrower proximate the bottom
to account for bending stress. Further, the inner g surface may be attached to the side
wall in pieces or have grooves (e.g., vertical s) in one side of the al to enable
the material to flex more easily and bend with the wall of the mold. FIG 12, discussed
further below, illustrates an e embodiment in which a side wall 211 includes a
graphite 271 inner g surface.
[0048] depicts the back side of the side wall assembly 210 illustrating the top
actuation plate 218 adjacent to top plate 216 and the bottom actuation plate 217 adjacent to
the bottom plate 212. Also visible is the curvature 214 of the bottom plate visible below
the back side of the side wall 211 as the side wall is rated in a substantially straight
configuration. An end plate 320 attaches the top actuation plate 218 to the bottom
actuation plate 217 such that they move together in unison through movement of actuation
assembly 330. The actuation assembly may be any of a variety of mechanisms for
providing the actuation necessary to achieve the motion described herein. The motion
includes substantially linear motion along arrow 340, where the actuation plates 217 and
218 are configured to move along a longitudinal axis defined by the side wall assembly
210. The side wall 211 is attached to the actuation mechanism through force ing
members 310. This motion, as described r below, imparts a bending force on the side
wall 211.
illustrates the mechanism used to impart a bending motion to the side
wall 211 using the ion plates 217, 218 as actuated by actuation assembly 330. The
actuation assembly may e a linear actuator, a ball screw mechanism, a rack and
pinion mechanism, hydraulic piston, pneumatic piston, solenoid, or the like. While the
illustrated embodiment of illustrates a screw mechanism, which may be turned by
hand, embodiments may generally include an automated actuation assembly to impart
movement of the side walls 211. As shown herein, the actuation may be performed
through generally linear nt and translated through action plates 217, 218 to cause
a bend to be imparted on the side wall 211. The actuation may be automated through
actuator means such as a solenoid, electric motor, hydraulic actuator, or the like.
Optionally, actuation may be manual, as depicted in including a turn-handle 330
which may be configured to move the actuation plates relative to the side wall assembly
by virtue of a helical screw adjustment mechanism.
shows a portion of the side wall 211 including a force receiving member
310 attached thereto at a contact point by arms 410 and ts 420. The force receiving
member 310 may be attached to the side wall at one or more t points or locations
along a height of the side wall 211, the height extending along an axis orthogonal to the
image of illustrates a perspective view of the back of another portion of the
side wall 211 including force receiving members 310 attached by arms 410 and brackets
420 to attachment points 450 defining contact s for the force receiving members
310. As shown, a plurality of attachment points 450 are disposed along the back of the
side wall 211 such that the force receiving members 310 can be repositioned along the
length of the side wall 211 as needed to produce the necessary contour of the side wall 211
through an application of force through force receiving members 310. The attachment
points provide a secondary function of ng the flexible bladders that form cooling
fluid channels 460 and 465 as described further below using fasteners that may be use to
attach the flexible bladders and to also attach the brackets 420 to the side wall 211 as
appropriate. In the illustrated embodiment, there are two cooling fluid chambers 460 and
465, with attachment points 450 disposed on either side of the fluid channels and n
the fluid channels. Attachment of the force ing members 310 at three locations along
the height of the side wall 211 es an even distribution of forces applied to the force
ing members 310 at a position along the side wall from the top of the side wall to the
bottom of the side wall, minimizing angular deflection of the sidewall. However, as
described further below, forces may be applied distinctly from the top to the bottom of the
force receiving members to induce a taper as appropriate according to some example
embodiments.
[0051] While the illustrated embodiments described herein generally depict two fluid
chambers (460 and 465), there may be more or fewer fluid chambers based on the desired
design configuration. A single fluid chamber may be used in some ments to
provide cooling fluid flow through the side wall 211. Optionally, more than two fluid
chambers may be used, particularly in an embodiment in which ent flow rates or
pressures may be desirable through orifices ated with each of the fluid chambers.
rly, while three attachment points are shown for each of the force receiving
members 310, ments may include fewer or more attachment . According to
some embodiments, the force receiving members may be attached to the side wall only at
a single location, while in other embodiments the force receiving members may be
attached to the side wall at two, three, or more locations.
Referring back to and with reference to each of the actuation
plates 217, 218 include an angled slot in which a respective end of the force receiving
members 310 are disposed. This angled slot is represented by dashed line 440 of
The top plate 216 and bottom plate 212 also include slots in which respective ends of the
force receiving members 310 are received. These slots are perpendicular to the line along
which the side wall extends, and are represented by dashed line 430 of
rates the end portion 314 of force ing members 310 that are received in slots
440 of the actuation plates, while end portion 312 of the force ing members 310 are
received in a respective one of the top plate 216 or bottom plate 212 in slot 430. The end
ns 312, 314 of the force ing members 310 may include bearings or reduced
friction surfaces in order to transmit forces between the slots 430, 440 and the force
receiving members 310 as described herein, while reducing the frictional forces involved
in the interface between the force receiving members 310 and the slots 430, 440.
[0053] According to the illustrated embodiment of as the actuation plates 217,
218 are advanced simultaneously by ion assembly 320 in the direction of arrow 445,
the slot 440 also moves in the direction of arrow 445 with the actuation plates relative to
force receiving members 310. The force receiving member 310 is held fixed in the y-axis
(shown in FIGS. 7 and 9) by virtue of the force receiving member being received in the
slots 430 of the top plate and bottom plate, restricting nt or displacement of the
force receiving members to only along the x-axis. As the force receiving member is moved
along slot 440 as the ion plate is moved, the force receiving member 310 is
displaced along the x-axis in slot 430 of the top plate and bottom plate. With the ends of
the side wall 211 held substantially fixed relative to the x-axis, the movement of force
receiving member 310 along slot 430 results in a displacement of the force receiving
member 310 from its original position, and a bend is imparted on the side wall 211 as
shown in based on the displacement of the force receiving member, which may be
rated for ease of understanding. The forces between the actuation plates 217, 218
and the force receiving member 310 and the top 216 and bottom 212 plates and the force
receiving member 310 are transmitted between the slots 440 and 430, respectively, and the
bearing surfaces of the force ing member 312, 314 shown in This enables a
smooth transition as the profile of the side wall 211 is changed during the casting process.
This bend in side wall 211 enables the profile of the mold cavity to be cally
adjusted during casting to reduce swelling of the butt of the ingot during the casting start-
up phase.
While the above-described and illustrated embodiment es actuation
plates 217, 218 that move simultaneously and in synchronization, example embodiments
described herein may provide an actuation mechanism that allows the top actuation plate
218 to be moved independently from the bottom actuation plate 217. Disconnecting the
fixed relationship between the top actuation plate 218 and the bottom actuation plate 217
allows a curvature in the side wall 211 to be different between the top and bottom of the
side wall, such as a tapered opening from a wider curve at the top of the side wall 211 to a
narrower curve at the bottom of the side wall. Through disconnection of fixed relationship
between the top actuation plate 218 and the bottom actuation plate 217, the displacement
of the force receiving member 310 may be different from the top of the force receiving
member to the bottom force receiving member. This additional degree of freedom may
enable better l over the e of the ingot cast from the mold by permitting
differing displacement along the x-axis between the top of a side wall and the bottom of
the side wall. The separate actuation may include any of the mechanisms described above
duplicated for top and bottom actuation plates, or using a single actuation mechanism with
an adjustment allowed between the actuation mechanism and one or both of the top 218
and bottom 217 actuation plates. Such an ment mechanism may be a mechanism that
enables a length to be altered between the actuation mechanism and one or both of the
actuation plates, y enabling an offset to be imparted between the top ion plate
and the bottom actuation plate.
Further, while the illustrated ment of FIGS. 3-9 depict actuation plates
that engage each of the force receiving members, according to some embodiments,
multiple actuation plates may be used for each of the top and bottom actuation plates to
de-link the displacement of the force receiving members. As will be described further
below, other mechanisms may be used to displace the force receiving members, and these
mechanisms may also displace the force receiving members independently from one
another. According to an embodiment implementing actuation plates as in FIGS. 3-9,
multiple actuation plates may be used, with each actuation plate engaging one or more
force ing members, and each ion plate may be independently actuatable to
provide ent displacements at each force receiving member as ary to achieve
the desired side wall profile during casting.
In response to a bend introduced in the side wall 211 of the mold cavity
through displacement of the force receiving members 310 along the x-axis shown in FIGS.
7 and 9, the ends of the side wall will tend to pull in toward the middle of the side wall
211 as the wall is made of a material such as a metal which may be flexible, but resists
elastic stretching. To odate this, the ends of the side wall 211 may be held in an
ement that allows some degree of movement n different curvatures of the
side wall 211 introduced by the mechanism described above. illustrates such an
2018/054214
arrangement, with the side wall 211 held between an end plate 480 and the fluid conduit
block 260. The end plate 480 may be fastened at the top and bottom to a respective one of
the top plate 216 and bottom plate 212, maintaining the end plate 480 in a fixed position
relative to the end plate assembly 210. As the side wall 211 is moved between a straight
profile and a curved profile, the ends of the side wall 211 may slide relative to the end
plate 480 and fluid conduit block 260, enabling the necessary freedom of the ends of the
side wall 211 to preclude unnecessary stresses on the bending middle portion of the side
wall 211 between the two ng ends. A force may be applied to the fluid conduit
block 260 in the direction of the end plate 480 to capture the side wall 211 between the
end plate 480 and the fluid conduit block 260. r, the fluid conduit block may be
attached to the side wall 211 and move in concert with the side wall through the relatively
small sliding movement of the side wall 211 during bending of the side wall. The end plate
480 may ally be part of the end wall assembly, such that the end wall assembly is
attached to the side wall assembly through the top plate 216 and the bottom plate 212 to
form the mold cavity.
The illustrated embodiment of FIGS. 7-9 depict isms by which a force
is applied to the side wall 211 of the mold cavity to introduce a curvature to the side wall.
These forces may be substantial, and the interface between the force receiving members
310 and the side wall 211 may experience relatively high stresses. In order to reduce or
mitigate these stresses, a force distribution mechanism may be used to more evenly
distribute the forces between the force receiving members 310 and the side wall 211. illustrates an e embodiment of a bogie 411 force distribution member that may
help mitigate stress concentration along the side wall 211. As shown, the bogie 411 rigidly
connects pivot points 421 to the force receiving member 310, while being pivotally
attached to both the force receiving member 310 and the side wall 211 via attachment
points 420. This arrangement promotes force distribution from the force receiving member
310 along a portion of the sidewall 211 spanned by the bogie 411.
Also rated in is a fixed on element 520, as described in
greater detail below, but which remains at a fixed point within the side wall assembly 210
and applies a resistive force against the side wall 211 as the force receiving members 310
displace the side wall forming a curved side wall. The fixed position element 520 may be
fixed only at the pivot point 521 such that the on of the fixed position element 520
s constant during deformation of the side wall 211. However, according to some
ments, the fixed position element 520 may pivot about axis 521 in order to better
distribute forces along side wall 211. As shown, the fixed position element 520 is
pivotable about axis 521, and includes arms 522 which are pivotably attached to fixed
on block 525 at pivot points 523. The fixed position block 525 distributes forces
from pivot point 521 to arms 522. Arms 522 distribute forces to attachment points 524. In
this manner, forces n the pivot point 521 and the side wall 211 are distributed along
the wall at attachment points 524 to reduce any stress concentrations along the wall which
may lessen the likelihood of failure.
During the casting process, as material exits the mold cavity in response to the
starter block 157 ing downwardly as shown in cooling of the material
exiting the mold cavity is necessary to properly form the ingot 160. This cooling is
ted by the use of cooling fluid or coolant sprayed from orifices ate the
bottom of the side wall 211 in the direction of the material exiting the mold cavity. illustrates a cut-away view of a side wall 211 including cooling fluid chambers 460 and
465 formed by flexible bladder 462. Also shown is a fluid chamber 261 formed into the
back side of side wall 211 and separated from the fluid chambers 460 and 465. The
flexible bladder 462 may be made of a silicone rubber with a nylon reinforcement.
Silicone withstands high atures, particularly in short bursts, and sluffs molten
aluminum with relative ease. The nylon rcement may keep the flexible bladder 462
from stretching which could create pressure variations and weaken the flexible bladder.
Fluid chamber 261 is ured to carry lubricating fluid along the length of the side wall
211 and is in communication with the plurality of orifices 262 (of which a cross-section of
one is shown in ), which provides lubricating fluid to the face of the side wall 211.
The lubricating fluid may be provided to the fluid chamber 261 at a relatively high
pressure and release into the mold at a more uniform and lower pressure. The lubricating
fluid exits the orifice 262 flowing generally downwardly along the casting surface of the
side wall 211 rather than spraying outwardly from the side wall to e a layer of
lubrication between the casting and the side wall 211. Each of the plurality of orifices 262
for providing lubricating fluid to the face of side wall 211 may be configured to allow
lubricating fluid to flow substantially evenly across the length of the side wall 211 using as
many or as few lubricating fluid orifices as deemed appropriate for the size of the mold
and the material to be cast. According to some embodiments, the orifices may be round
and spaced apart along the side wall 211, while in other embodiments, the orifices may be
elongate slots extending along the side wall 211. In an embodiment in which the es
are elongate slots, the slots may be fed from fluid chamber 261 along pathways to the
WO 29634
elongate slots disposed on the side wall 211. This may enable elongate slots to provide a
"curtain" of lubricating fluid down the side wall as lubricating fluid exits the orifices.
As described above, the walls of the mold, including the illustrated side wall
211 and end walls, may include an inner casting material such as graphite.
illustrates such an example including a graphite inner casting material on the inner surface
of the illustrated mold wall. This material may be adhered to the side wall 211 of the mold
or mechanically attached h any available means. The illustrated inner casting
material 271 extends along only a portion of the height of the side wall 211, but may
extend the full height of the wall. Further, the inner casting material may include es
there through to allow lubricant from orifices 262 through the inner casting material, or
alternatively, the lubricant from orifices 262 may supply lubricant to the porous inner
casting material which may then bute the ant along the face of the inner casting
material by virtue of the porous nature of the material.
illustrates an example embodiment of an inner casting material 271
secured to the face of a mold wall 211. As shown, the inner casting material 271 es a
taper from a relatively wider ess 272 ate the top of the mold wall, and a
narrower thickness 273 proximate the bottom of the mold wall 211. The example
embodiment of includes an inner casting material that extends from a location
near the bottom of the mold wall 211 to the top of the mold wall. A ledge 274 is
incorporated into the side wall 211 onto which the inner casting material 271 rests. This
may enable the inner g material 271 to be inserted from a top of the mold, and may
reduce the reliance on the adhesive or mechanical fastening means between the inner
casting material 271 and the mold wall 211 as the ledge 274 may support the inner casting
material 271 and preclude nt of the inner casting al in a downward direction
as material is cast through the mold.
As noted above, embodiments may include any number of cooling fluid
chambers, where each cooling fluid chamber may feed one or more sets of orifices for
providing cooling fluid to the cast part as it exits the mold. As shown in , cooling
fluid chambers 460 and 465 may be configured to carry g fluid to two sets of
cooling orifices 264 and 266. The side wall assembly may include baffles disposed
between the cooling fluid chambers 460, 465, and the side wall 211, where baffle orifices
may be sized and spaced to regulate fluid flow and pressure through the es 264 and
266. As shown in the embodiment of , a first set of baffle orifices 263 may
regulate the cooling fluid flow through fluid passage 270 in the side wall 211 to a first set
of orifices 266. A second set of baffle orifices 269 may regulate the cooling fluid flow
through the second set of es 264. The use of a baffle plate 268 with orifices 263, 269
arranged therein may regulate the fluid flow and pressure, but may also enable fluid to
flow from orifices 264, 266 in a laminar flow pattern along paths 265 and 267 based, at
least in part, on the length of the fluid channel between the baffle plate 268 orifices 263
and 269 and orifices 266 and 264, respectively. While both orifices 264 and 266 are
visible in the ay view of , along with the fluid flow paths for each, it is
appreciated that both orifices and associated fluid flow pathways may not be visible in a
physical section view. The cut-away view of is ed for illustration and ease
of tanding. While the orifices 264, 266 are rated as round, embodiments may
include orifices 264, 266 which are elongate along the side wall 211. This may enable a
different cooling fluid flow pattern from the orifices for cooling the cast part as it exits the
mold.
According to an example embodiment, a baffle plate between the fluid flow
chambers 460, 465 and the orifices 263, 269 may have slot-shaped apertures arranged
vertically to reduce back pressure within the fluid chambers. This may allow less
restrictive fluid flow to the orifices. However, embodiments may include flow restrictors
disposed proximate the cooling orifices 265, 267 to promote even fluid flow among the
orifices. Between the baffle plate and the ctor, consistent, even fluid flow can be
ed through the orifices 265, 267.
According to the illustrated embodiment, fluid chamber 465 may be in fluid
communication with cooling orifices 264, which may each be arranged at an angle with
t to the side wall 211. In the depicted embodiment, cooling es 265 are arranged
at an angle of forty- five degrees relative to the side wall 211, as shown by arrow 265
indicating the direction of fluid exiting the first plurality of cooling orifices 264. The
second plurality of cooling orifices 266 may be arranged to direct cooling fluid at a
different angle as shown by arrow 267, which is illustrated at an angle of -two
degrees relative to the side wall 211. However, the second plurality of cooling orifices
may be in fluid communication with cooling fluid chamber 460 rather than chamber 465.
In order to supply cooling fluid from the cooling fluid chamber 460 to the plurality of
orifices 266, a channel 270 may be machined or ise formed into the back face of the
side wall 211, beneath the substrate 280 on which the cooling ls are supported. A
channel 270 may be present for each of the second set of g orifices 266, or
alternatively, channels 270 may exist at a plurality of locations along the length of the side
wall 211 in cooperation with a channel closer to the second set of cooling orifices 266
extending longitudinally along the side wall 211 in a manifold ement.
According to the illustrated embodiment, the cooling fluid flow through each
of the first plurality of orifices 264 and the second plurality of orifices 266 may be
independently fed by a respective cooling fluid chamber 460, 465. This configuration
enables a cooling profile to be generated according to the type of material being cast with
the appropriate flow rates and spray patterns from the respective set of g orifices.
The fluid t block described above with t to may include separate
valves for controlling the cooling fluid flow to each of the cooling fluid chambers 460,
465. Separately lled valves may enable ndent flow regulation through the
chambers and thus through the respective orifices to which the chambers are in fluid
communication. Optionally, cooling fluid temperatures may be separately controlled to
e even further control over the cooling of the material exiting the mold. In order to
accomplish this, the fluid conduit block may receive cooling fluid from two separate
sources through two separate inlets, and control the flow from the separate inlets
independently through each of the g fluid chambers 460, 465.
Further, while the arrows 265 and 267 depict a general direction of cooling
fluid exiting the orifices 264, 266, respectively, the spray patterns and fluid flow rates may
be designed according to a preferred spray pattern based on the cooling requirements of
the material being cast. Cooling fluid may also be selected based on the g
requirements of a particular material being cast. Such g fluid may include, for
example, water, ethylene glycol, propylene glycol, Organic Acid Technology (OAT)
cooling fluid, or other fluid suited for drawing heat away from the cast part. The angle of
the cooling orifices 264 and 266 may each also be configured for a specific angle of
impingement on the cast part, which may be at an angle to encourage laminar flow at the
orifice exit and turbulent cast part cooling fluid flow as the cooling comes into contact
with the cast part. The angle of flow from the cooling orifices 264 and 266 may be in the
range of about 0 degrees ted down, substantially parallel to the side of the cast part
exiting the mold) to about 90 degrees (directed perpendicular to the side of the cast part
exiting the mold toward the cast part). This angle may be established based on
characteristics of the material to be cast in the mold, for example.
According to some embodiments, fluid conduit block 260, as shown in FIGS.
and 6, may be configured to control the fluid flow and pressure along the fluid channels
in communication with the orifices 264, 266 ing to established cooling needs of the
material being cast through use of one or more valves, which may be disposed within the
fluid conduit block 260. In an embodiment in which the fluid conduit block 260 includes a
valve for each coolant fluid chamber, the fluid conduit block may be configured to
independently control the flow and pressure along chambers 460 and 465 as . The
fluid flow levels and pressures may be established based on an alloy composition,
temperature of the material being cast, the speed at which the material is being cast (i.e.,
the speed at which the starting block descends into the casting pit), or other ties that
affect the casting process. The fluid channels, as described further below, may be flexible
such that flexing of the side wall 211 does not adversely affect or impact the integrity of
the fluid channels.
Each of the fluid chambers 460 and 465 may be defined by a flexible bladder
462, such as a heat-resistant silicone or similar material. While a separate flexible bladder
may be used to define each cooling fluid chamber, according to the illustrated
embodiment, a single flexible bladder 462 is used to define both cooling fluid chambers
460, 465, where the flexible bladder webbing may be captured between fasteners 450 and
their ponding fastener holes within the side wall 211. The baffle plate 261 may also
be captured between the flexible bladder webbing and the side wall 211 using those same
fasteners. The flexible bladder g may also be d to the baffle plate 261 using
an adhesive or high-temperature sealant. Optionally, the flexible bladder material may be
fiber-reinforced, multi-material, or geometrically layered to improve life of the chambers
460, 465. The bladders may be flexible to accommodate the bending of side wall 211,
though sufficiently resilient to enable a fluid pressure to be applied to the fluid within the
chambers to facilitate the appropriate flow rate and spray pattern from the es 264,
266.
[0069] In addition to providing cooling fluid to the es 264, 266, the cooling fluid
chambers 465 and 466 e a cooling effect on the side wall 211 itself. Cooling fluid
chambers 465 and 466 are arranged in a manner that facilitates heat extraction from the
back face of the side wall 211 into the cooling fluid. This side wall g effect further
reduces the temperature of the side wall 211 proximate the ating fluid channel 261 to
avoid over g the lubricating fluid which can result in ure evaporation or
burning of the lubricating fluid. Cooling of the side wall 211 using g fluid chambers
460 and 465 further reduces the likelihood and degree to which lubricating fluid would
burn or evaporate as it flows down along side wall 211 with the cast material.
Example embodiments have been described and illustrated herein as
incorporating flexible side walls of a direct chill casting mold with fixed profile end walls.
However, ments described herein with respect to the side walls may optionally
include end wall assemblies having uctions similar to those of the lls
described herein. End walls that are sufficiently long to result in swell of the cast material
during a start-up phase of the casting process, or in need of profile correction may be
ured to be flexible in the same or a similar manner as described herein with t
to the side walls. The flexibility of end walls may further reduce swelling of the ingot butt
during the start-up phase and may decrease waste while increasing the efficiency and
output of a direct chill ingot casting mold.
The above described and illustrated example embodiments include a plurality
of force applying members which, responsive to a force received, induce a bend in a side
wall (or end wall) of a mold. illustrates a representation of a side wall assembly
500 of a mold simplified for ease of understanding. As shown, the e of a top plate
505 includes a side wall 511 disposed in a curved position. The curved position illustrated
is achieved by to displacement of the force receiving elements 510 through forces applied
to force receiving elements 510 in the direction of arrow 515. Embodiments described
herein may optionally include fixed position elements that resist movement of the side
wall 511. depicts fixed position elements 520, which may be securely fastened to
the top plate 505 and bottom plate (not shown) of side wall assembly 500. The fixed
position elements 520, which are also depicted in may be configured to ensure the
appropriate curvature shape is ed in se to the force applied to the force
receiving elements 510. In this , fixed position elements 520 may limit maximum
deformation of the side wall or end wall at a specific position along the wall.
[0072] The forces applied to the force receiving elements 510 may be different across
a side wall. For example, as shown in , the three force receiving elements 510 may
be ured to be displaced by a predefined amount from a straight uration. This
displacement will define the curvature imparted to the side wall 511. To achieve the
desired ure, the force applied at the middle force receiving element 510 may be
different from those nt thereto. For example, applying an equal force to each force
receiving element 510 may result in an arc with maximum displacement at the middle of
the curve of the side wall 511, where the middle force receiving element is. However, the
desired curvature of the wall may not include a m degree of curvature proximate
the center of the wall 511, and may actually include a relatively straight section along all
WO 29634
three force receiving ts. In such an embodiment, the displacement for each of the
force receiving elements may be equal, while the middle force receiving element 510 may
actually apply a force to the side wall 511 in a direction opposite arrow 515, opposing the
ure of the wall 511 to achieve a flatter curve in the middle of the side wall. As such,
cement of the force receiving s 510 may critical to establish the shape of the
curve of the side wall, while the forces are applied as ary to e the desired
displacement.
The adjustment of the ure of a side wall or end wall of a direct chill mold
during the casting process may be controlled using a plurality of different methods. For
example, a cast material may have a casting profile that es parameters with respect to
casting speed (e.g., flow rate of the liquid cast material and descent speed of the starter
block), the temperature of the liquid cast material entering the mold cavity, the flow
rate/pressure of the g fluid through the cooling orifices, the flow rate/pressure of the
lubricating fluid through the lubricating orifices, and a curvature profile for the material at
each phase of the casting process. The curvature profile may be adjusted from a first
position during the start-up phase of g, to another curvature profile during the
steady-state phase, to another curvature profile during the end phase, and any number of
curvature profiles between these phases (e.g., a dynamic steady change between the
different phases). In such an embodiment, a ller may dictate the shape of the
curvature of the side walls and/or end walls throughout the casting process responsive to
the phase of casting. Feedback of properties of the material being cast may not be
necessary in such an embodiment.
According to some embodiments, the curvature profile of the walls of the mold
may be determined based on a closed-loop feedback system. A controller may receive
temperature information (e.g., of the liquid casting material, the cast material exiting the
mold, mold temperature, etc.), casting speed (e.g., the speed of descent of the starter block
and platform), dimensional information (e.g., dimensions of the cast part as it exits the
mold cavity or a predefined distance below the mold cavity exit), stress and/or strain
feedback, or other ation related to the casting process, and use this information to
establish the appropriate curvature profile of the wall. A plurality of sensors may be
dispersed around the exit of the mold cavity, such as thermal sensors to detect the
ature of the casting exiting the mold, or distance sensors ured to measure the
dimensions of the casting exiting the mold. These sensors may provide feedback to the
controller to determine the appropriate curvature profile given the data with respect to the
casting exiting the mold cavity.
While example embodiments described herein may be implemented to reduce
or control butt swell of a cast part, example embodiments may optionally be implemented
to preclude or mitigate cast parts getting stuck within the mold. For example, butt curl and
ively hot casting ions of a cast part such as an ingot during the g process
may cause an interference fit of the cast part within the mold, where the mold walls (side
walls, end walls, or both) become engaged by the cast part in a manner that des the
cast part 160 from exiting the mold assembly 200 as the starter block 157 descends into
the cast pit. These conditions which lead to an interference between mold and cast part
may lead to catastrophic failure, such as a mold over flow if not quickly corrected or
mitigated. During the steady-state portion of the casting process, various factors may
contribute to a cast part becoming hung up in the mold, such as improper lubrication,
abnormal cooling, or the like. During the end of the casting process, the cast part may
experience "reduced head shrinkage" and the flexible walls of the mold of example
embodiments may be controlled to accommodate this shrinkage. During the nt of
the side walls of the mold, a binding condition may occur where the cast part becomes
stuck or hung up in the mold. In each of these cases, while the causes may be different, a
cast part may become stuck within the mold which can lead to catastrophic failure if not
mitigated quickly.
Example embodiments bed herein may provide feedback from the mold
to a controller ting when a ion arises where the cast part is stuck or hung up in
the mold. The feedback to the controller may include one or both of two detected changes.
A first change that occurs in the casting process when the cast part is hung up within the
mold is that the casting fluid flow slows while movement of the starter block continues
downward into the casting pit. The casting fluid flow is controlled by the control pin and
spout orifice size based upon metal level feedback, such that if fluid flow is rising while
the starter block continues to descend, it is an indication that the cast part may be stuck in
the mold. The level of the molten metal in the mold may be maintained at a nt or
near constant level during casting through feedback of the level in the mold to a valve,
such as a control pin in a fluid flow tube, to adjust the flow according to the fluid level in
the mold. If this fluid flow control has to reduce fluid flow to maintain fluid level
unexpectedly, it may be a symptom of a cast part stuck in the mold cavity.
Similarly, if the casting fluid flow of a first mold cavity from among a plurality
of mold cavities is different and slower than the remaining cavities, this may be an
indication of a stuck cast part. A second change that may occur during casting that may be
indicative of a cast part stuck in a mold is resistance or feedback experienced by the
actuation mechanism that provides a curvature in the mold side walls. The mold side walls
may be held in a predetermined position by the actuation ism, and when the cast
part becomes stuck or hung up in the mold, a force may be applied by the cast part onto
the mold walls. In the case of an electric actuation mechanism, the actuation mechanism
may experience a rise or spike in amperage or current draw at the actuation ism
indicating a resistive force opposing the actuation mechanism. This spike may be
tive of the hanging up of a cast part in the mold. In the case of a hydraulic ion
mechanism, a spike in pressure or current draw on a hydraulic pump may similarly be
indicative of a cast part being hung up in the mold.
Still r mechanism to detect a cast part stuck in the mold may be through
a weight or force on the starting block 157 and platform 159 (as shown in . During
casting, the weight of the cast part will se as the starting block descends into the
casting pit due to the se in material flowing into and g the mold cavity. If the
weight decreases at any point during casting, it is an indication that the starting block no
longer bears the full weight of the cast part. This may be an indication of a cast part stuck
in the mold. The decrease in weight on the starting block may be detected by a force
measurement transducer or other sensor on the ng block or on the platform. However,
the reduced weight on the starting block may also be detected through the mechanism
lowering the platform and starting block. For example, a hydraulic system used to lower
the rm and starting block may control the lowering of the platform through
controlling fluid flow from a chamber. Responsive to an unexpected change in fluid flow
or fluid flow pressure, a controller of the system may determine that the weight on the
starting block has decreased.
Responsive to an indication of a cast part being hung up in the mold, whether
h one or both of an unexpected slowing of the casting fluid flow or a spike or
increase in the hydraulic pressure or electrical current of the actuation mechanism, the
controller may adjust the shape of the walls of the mold, such as the side walls, in an effort
to cause the cast part to break free or separate from the mold, allowing lubricant to reach
between the cast part and the mold walls. This change in shape may be caused by the
2018/054214
controller actuating the actuation mechanism in such a way as to encourage the cast part to
descend from the mold cavity along with the starting block down into the casting pit.
The actuation mechanism for inducing the appropriate curvature profile is
described and illustrated above to include a pair of actuation plates and an actuation
mechanism to move the actuation plates. However, other isms may be ed to
provide forces to the force receiving members to impart a curvature to the side walls or
end walls of a mold. illustrates such an example ment including the side
wall assembly 500 arrangement of . The force receiving s 510 of
are connected to ors 530 which can push or pull the force receiving members along
the X-axis (e.g., in the direction of arrow 515 or opposite there to). The example
ment of may include actuators 530 that are linear ors to ull the
force receiving members 510. Actuators may optionally include rotational actuators that
turn a gear, such as a pinion gear on a rack gear to impart a force to force receiving
member 510, or a ball screw or worm gear that is rotated to impart a force on the force
receiving member 510. As noted above, the actuators 530 may be able to independently
control displacement of force receiving members 510 individually or in sub-sets.
In an example embodiment in which the actuators 530 function as described
with respect to , multiple molds suspended within the same mold frame can benefit
from equal and te forces applied by the actuators 530. illustrates a plurality
of mold assemblies 540 ed within mold frame assembly 545. The mold assemblies
540 may be attached to the mold frame assembly 545 in any conventional manner to
support the mold assemblies within the frame as the mold frame ly transitions
between a substantially vertical position in which the mold assemblies are positioned onend
, to the substantially horizontal on in which the mold assemblies are suspended
during casting using the mold cavities 550. As shown, the three illustrated mold
assemblies 540 include two pairs of adjacent side wall assemblies 560. During casting,
each of the mold assemblies are ideally at the same stage of the casting phase at the same
time due to a uniform material being cast in each of the mold cavities 550 and a common
platform on which the three starter-blocks for the molds are descending simultaneously.
As such, the curvature profile of the side walls of each mold should be the same. The
adjacent side wall assemblies 560 would then be providing equal and opposite forces to
their respective side walls.
illustrates an example embodiment of a pair of adjacent side wall
assemblies 560 from an adjacent pair of mold assemblies. In such an embodiment, the
benefits of the equal and opposite applied forces can be realized. In the embodiment of
, actuators 530 can be disposed between the pair of adjacent side wall assemblies
560 and configured to apply forces that are equal and opposite to an opposing pair of force
receiving elements 510. In this manner, the actuators remain in a neutral-force condition
regardless of force applied to the force receiving elements 510. This enables the support
structures that support these actuators to be less substantial and not require reinforcing
superstructure to preclude the mold assemblies from bending based on the forces exerted
by the actuators 530. While illustrates shared actuators 530, example
embodiments may include individual actuators for each force receiving member 510 of
each side wall assembly, but may enable ng between corresponding actuators from
adjacent side wall assemblies 560. This enables the side wall assemblies to cooperate to be
force-neutral while still producing the necessary curvature profile in the side wall. Side
wall assemblies that do not have an adjacent side wall assembly may require increased
ural support relative to those side wall assemblies that are nt to other side wall
assemblies. The increased structural support may be modular and removable, while the
coupling of adjacent actuators may be interchangeable to enable molds to be placed within
a frame without regard to their order, and enable coupling between any pair of adjacent
side wall assemblies and reinforcing of any non-adjacent side wall assemblies.
The dynamically able side walls of e embodiments described
herein may be used to ish the e of the cast part as it exits the mold cavity and
cools. However, ing to some embodiments, the cally adjustable side walls
may optionally be used to aid in ng the starting block to the mold cavity. Alignment
of the starting block with the mold cavity is important to ensure no casting fluid leaks at
the start to the casting process. While a mold frame may be moved to align with a starting
block through, for example, electric, pneumatic or hydraulic actuator means, ments
described herein may use the dynamic flexibility of the mold side walls to align the mold
cavity to the starting block. The starting block 157 may be positioned on a platform 159.
The interface between the starting block 157 and the platform 159 may be a reduced
friction interface, such as through use of a lubricating material (e.g., grease, oil, graphite,
etc.) or using an air n with air fed h the platform to between the platform 159
and the starting block 157. One or more alignment features may extend below the mold
cavity to be used as guides to guide the starting block 157 into engagement with the mold
. Prior to casting, as the platform is raised to engage the starting block 157 with the
mold cavity, or as the mold is lowered into engagement with the starting block, the side
walls of the mold cavity may be adjusted to open the mold cavity. Opening of the mold
cavity using the dynamically adjusted side walls may provide a larger area into which the
ng block 157 may be received, helping ease ent.
Bringing the starting block into engagement with the mold cavity may be aided
by alignment features of the mold, and once the starting block 157 is within the mold
cavity, the dynamically adjusted side walls may be adjusted to a smaller opening to
provide proper clearance with the ng head for cast start. In the event the starting
block is not ly aligned or centered within the mold cavity, the adjustment of the side
walls of the mold cavity may move the starting block such that it is centered within the
mold cavity. The d friction surface between the starting block 157 and the platform
159 may facilitate this movement. Through this mechanism, alignment between the
starting block 157 and the mold cavity may be more easily achieved.
Many modifications and other embodiments of the inventions set forth herein
will come to mind to one skilled in the art to which these inventions pertain having the
benefit of the teachings presented in the foregoing descriptions and the ated
drawings. Therefore, it is to be understood that the inventions are not to be limited to the
specific ments disclosed and that modifications and other embodiments are
intended to be included within the scope of the appended claims. Although specific terms
are employed , they are used in a generic and descriptive sense only and not for
purposes of limitation.
Claims (17)
1. An tus for casting material, comprising: first and second opposing side walls; first and second end walls extending between the first and second side walls, wherein the first and second opposing side walls and first and second opposing end walls form a generally rectangular shaped mold cavity; and two or more force receiving elements; wherein at least one of the first and second opposing side walls comprises two or more contact regions, each of the two or more force receiving elements attached to at least one of the first and second opposing side walls at a respective contact region at two or more ng attachment points, wherein each of the two or more contact s are ured to be displaced relative to a straight line between a first end of the at least one of the first and second opposing side walls and a second end of the at least one first and second opposing side walls in response to receiving a respective force applied externally from the mold cavity, wherein the respective cement at a first of the two or more t regions relative to the straight line is different from a displacement at a second of the two or more contact regions relative to the straight line, wherein the force applied to the respective force receiving element is distributed across the two or more pivoting attachment points, and wherein a respective force at each of the two or more contact regions changes a curvature of the at least one of the first and second opposing side walls between the first end and the second end of the at least one first and second opposing side walls.
2. The apparatus of claim 1, wherein the tive force at the first of the two or more contact regions comprises a force in a first direction, wherein the respective force at the second of the two or more contact regions comprises a force in a second direction, opposite the first direction.
3. The apparatus of claim 1, wherein the respective force at the first of the two or more contact regions comprises a force of a first magnitude in a first direction, n the respective force at the second of the two or more contact regions comprises a force of a second magnitude in the first direction, wherein the second magnitude is different from the first magnitude.
4. The apparatus of claim 1, wherein the first and second opposing side walls comprise an inner casting face and an outer surface, each of the first and second opposing side walls r comprising a flexible bladder disposed along the outer surface, n a cooling fluid r is defined between each respective opposing side wall and the respective flexible bladder.
5. The apparatus of claim 4, wherein the casting surfaces of each of the first and second opposing side walls comprise a plurality of orifices in fluid communication with their respective fluid chamber.
6. The apparatus of claim 5, further sing a baffle disposed between a cooling fluid chamber and the respective side wall, wherein the baffle comprises a plurality of flow-restricting
7. The apparatus of claim 6, wherein the plurality of orifices in each of the first and second opposing side walls are configured to direct cooling fluid from the tive cooling fluid channel toward a cast material as the cast material advances past the g surfaces of the first and second opposing side walls.
8. The apparatus of claim 1, further comprising: two or more fixed position members, wherein the two or more fixed position members are configured to resist movement of the first and second opposing side walls in response to a respective force applied at one or more of the two or more contact regions.
9. The apparatus of claim 1 , wherein the first and second opposing side walls each comprise an upper portion and a lower portion, wherein the upper portion of the at least one of the first and second opposing side walls is displaced proximate the first contact region a first distance relative to the straight line between the first end of the at least one of the first and second ng side walls and the second end of the at least one first and second opposing side walls, and the lower portion of the at least one of the first and second opposing side walls is displaced proximate the first contact region a second distance ve to the straight line n the first end of the at least one of the first and second opposing side walls and the second end of the at least one first and second opposing side walls, thereby ng a taper between an upper portion of the mold cavity and a lower portion of the mold cavity.
10. A system for casting metal comprising: a controller; a mold comprising: a first side wall; a second side wall opposing the first side wall; a first end wall; and a second end wall opposing the first end wall, wherein the first side wall, second side wall, first end wall, and second end wall cooperate to define a mold cavity having a mold cavity e; a first force receiving element attached at two or more pivoting attachment points to the first side wall located opposite the mold cavity, wherein a first force applied to the first force receiving element distributed across the two or more pivoting attachment points of the first force ing element is controlled by the controller and causes a first displacement of the first side wall at the first force receiving element; and a second force receiving element attached at two or more pivoting attachment points to the first side wall located opposite the mold cavity, wherein a second force applied to the second force ing t distributed across the two or more pivoting attachment points of the second force receiving element is controlled by the controller and causes a displacement of the first side wall at the second force receiving element, wherein the first displacement is different from the second displacement, wherein the first force receiving element and the second force receiving t are spaced apart from one another along a length of the first side wall between the first end wall and the second end wall.
11. The system according to claim 10, wherein the controller is ured to adjust the first displacement of the first force receiving element and the second displacement of the second force ing element during a casting process using the mold.
12. The system according to claim 11, wherein the controller adjusts the first displacement and the second displacement in response to at least one of a property of the metal being cast or a profile of the metal exiting the mold.
13. The system according to claim 11, wherein the first side wall and the second side wall of the mold each comprise a plurality of orifices for directing cooling fluid along metal exiting the mold during a casting process.
14. The system according to claim 13, wherein a cooling fluid channel is d along the first side wall outside of the mold cavity, wherein the cooling fluid channel is defined between the first side wall and a flexible bladder.
15. The apparatus according to claim 1, wherein the two or more force receiving elements are movable along a length of at least one of the first and second opposing side walls.
16. The system according to claim 10, wherein the first force ing element and the second force receiving element are movable along a length of the first side wall.
17. The apparatus of claim 1, wherein the two or more pivoting attachment points are displaced relative to one another along a length of the at least one of the first and second opposing side walls and connected to one another between the pivoting attachment points and a point at which the force is d to the respective force ing element. WO 29634
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/619,866 US10350674B2 (en) | 2017-06-12 | 2017-06-12 | Dynamic mold shape control for direct chill casting |
US15/619,866 | 2017-06-12 | ||
PCT/IB2018/054214 WO2018229634A1 (en) | 2017-06-12 | 2018-06-11 | Dynamic mold shape control for direct chill casting |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ759351A NZ759351A (en) | 2021-09-24 |
NZ759351B2 true NZ759351B2 (en) | 2022-01-06 |
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