U.S. patent number 3,847,206 [Application Number 05/262,509] was granted by the patent office on 1974-11-12 for self-centering bottom block assembly.
This patent grant is currently assigned to Kaiser Aluminum & Chemical Corporation. Invention is credited to John J. Foye.
United States Patent |
3,847,206 |
Foye |
November 12, 1974 |
SELF-CENTERING BOTTOM BLOCK ASSEMBLY
Abstract
This invention relates to a self-centering bottom block for a
direct chill (D.C.) casting apparatus. The assembly comprises a
bottom block which is slidably mounted on a supporting surface and
a retaining ring which loosely locks the bottom block to the
supporting surface but which allows for the horizontal movement of
the bottom block. As the assembly is raised into position, guide
buttons on the exterior surfaces of the assembly ride on guide
surfaces which are fixed spatially with respect to the mold bore
and thereby center the assembly within the mold bore. In another
embodiment of the invention, the bottom block assembly is provided
with a means which engages the ingot during the initial phases of
solidification and urges the ingot during the initial phases of
solidification and urges the ingot out of the mold but which
readily disengages the ingot after casting.
Inventors: |
Foye; John J. (Livermore,
CA) |
Assignee: |
Kaiser Aluminum & Chemical
Corporation (Oakland, CA)
|
Family
ID: |
22997813 |
Appl.
No.: |
05/262,509 |
Filed: |
June 14, 1972 |
Current U.S.
Class: |
164/425 |
Current CPC
Class: |
B22D
11/083 (20130101) |
Current International
Class: |
B22D
11/08 (20060101); B22d 011/08 () |
Field of
Search: |
;164/282,274,283 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,061,039 |
|
Dec 1959 |
|
DT |
|
725,323 |
|
Mar 1955 |
|
GB |
|
1,219,068 |
|
Jan 1971 |
|
GB |
|
Primary Examiner: Overholser; J. Spencer
Assistant Examiner: Rising; V. K.
Attorney, Agent or Firm: Calrow; Paul E. Lynch; Edward
J.
Claims
What is claimed is:
1. In a vertical D.C. casting apparatus for light metals comprising
an open-ended D.C. mold and a bottom block assembly adapted to be
inserted into said mold prior to casting the improvement
comprising
a. a bottom block adapted to be inserted into said mold and having
sufficient dimensions to thereby seal the discharge end of said
mold;
b. a vertically movable member smaller than the bottom block upon
which the bottom block is supported, the upper horizontal surfaces
of said member adapted for slidable contact with said bottom
block;
c. retaining means to loosely lock said bottom block to said
support member so as to allow horizontal movement of said bottom
block;
d. a plurality of vertically disposed guide surfaces below the bore
of said mold and separate therefrom and in a fixed spacial
relationship therewith, said guide surfaces being positioned no
closer than the projected perimeter of the mold bore and thereby
adapted to guide said bottom block into said mold bore; and
e. a plurality of guide means associated with said bottom block
which are adapted to ride on said guide surfaces as the bottom
block is raised into position within the mole or withdrawn
therefrom for aligning said bottom block with respect to said mold
and preventing contact between said bottom block and said bore.
2. The casting apparatus of claim 1 wherein the cross section of
said retaining means is generally L-shaped, the vertically
extending leg attached to the bottom surfaces of said bottom block
and the horizontally extending leg engaging the bottom surfaces of
said support member.
3. The casting apparatus of claim 2 wherein the horizontal
dimensions of the support member allow a horizontal movement of the
bottom block of from about 0.3 to 3 inches.
4. The vertical D.C. casting apparatus of claim 1 comprising
a. A plurality of vertically disposed, rotatable lock links mounted
in recesses in the periphery of said bottom block, the upper
portion of said lock link extending above the upper surface of said
bottom block and inwardly over a portion of said upper surface, the
end of said inwardly extending portion of the lock link provided
with a vertically disposed surface which is inclined in the
direction of the bottom block away from the vertical axis of the
bottom block; and
b. Means of urging the upper portion of said lock link into
engagement with said bottom block.
Description
BACKGROUND OF THE INVENTION
This invention relates to a bottom block assembly for use in the
vertical direct chill (D.C.) casting of metal particularly light
metals, such as aluminum.
In the D.C. casting of metals, molten metal is poured into an
open-ended tubular mold and begins to solidify into an ingot. Water
is sprayed onto the outside surfaces of the mold and the ingot as
it emerges from the mold to further cool the ingot and to assist in
solidifying the molten metal above the solidified portion of the
ingot. At the start of the casting operations, a bottom block or
starter block is inserted into the mold bore to seal the discharge
end of the tubular mold and to initiate the solidification of the
molten metal to form the ingot. Once solidification of the ingot
begins, the ingot is urged out of the mold by lowering the bottom
block into a pit situated below the casting apparatus. The bottom
block may be lowered by hydraulic or other suitable means. In the
past, there has been a continual problem with alignment of the
bottom block to avoid scuffing, gouging, or other damage to the
mold when the bottom block is inserted or withdrawn from the
mold.
In a conventional casting station, a plurality of molds (e.g., up
to 20 or more) are generally supported on a casting table which can
be moved out of position to remove the cast ingots from the pit. A
plurality of bottom blocks are rigidly supported on a vertically
movable support table. When the support table is raised to insert
the bottom blocks into the molds, the operators normally watch for
mold movement to determine misalignment of the molds and bottom
blocks. Due to the large number of molds at most casting stations,
it is impractical for the operators to check each mold to determine
if the bottom block is properly aligned. If mold movement is
noticed, the raising of the bottom blocks is stopped and the
operator, usually by force, repositions the mold. If the mold
position cannot be easily adjusted, then the mold would be loosened
from the casting table, aligned with the bottom block and
refastened to the casting table. In the case of a water-jacketed
mold, alignment of the mold and bottom block is more complicated
because the coolant and lubricant lines are attached to the mold,
and, frequently, these lines would have to be disconnected to
position the mold.
Misalignment of the bottom block assembly with respect to the mold
can be caused by many various factors. One of the most prevalent is
the removal of the ingot from the bottom block assembly after
casting. Usually, the bottom block is provided with projections,
such as wires, bolt heads and the like, around which metal can
solidify so that the bottom block can urge the solidifying ingot
out of the mold during the initial period of casting. Shortly after
the casting begins, the solidified portion of the ingot is
sufficiently heavy to urge the ingot out of the mold and at this
point, the bottom block functions to support and control the speed
of the ingot withdrawal. When the casting is completed, a lifting
device is usually employed to wrench the ingot away from the bottom
block. When the ingot is wrenched away from the bottom block,
frequently the bottom block would become displaced causing the
subsequent misalignment of the bottom block assembly with respect
to the mold bore.
Against this background, the present invention was developed.
SUMMARY OF THE INVENTION
The present invention provides an improved block assembly in which
a horizontally movable bottom block is guided into the mold bore
without the necessity of adjusting the horizontal position of the
mold assembly. The invention comprises a bottom block which is
slidably mounted onto a horizontal supporting surface. The bottom
block is provided with a retaining means which loosely locks the
bottom block to the supporting surface and which allows for
horizontal movement of the bottem block. Guide means on the
retaining means or the bottom block are adapted to slide along
guide runs which are in a fixed spatial relationship with respect
to the mold bore. As the bottom block assembly is raised into
position, the guide extensions contact the guide runs and thereby
align the bottom block with respect to the mold bore. With the
bottom block assembly of the present invention, reliance upon the
casting station operators for aligning the mold with the bottom
block is no longer necessary because no contact between the bottom
block and the mold surfaces can occur either in the insertion or
removal of the bottom block from the mold bore. Moreover, because
contact of the mold surfaces by the bottom block is eliminated by
the present invention, a substantial increase in the operational
life of the mold results. In a preferred embodiment of the present
invention, the bottom block assembly is provided with a means which
locks the forming ingot into position with the bottom block during
the initial portion of the casting but which will readily release
the ingot after the ingot is cast.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of one embodiment of the present
invention.
FIG. 2 is a perspective view and FIG. 3 is a cross-sectional view
of a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, the bottom block assembly 10 of the
present invention is generally shown in the mold bore 11 of
water-jacketed mold 12. The bottom block assembly comprises a
bottom block 13 having horizontal dimensions slightly less than the
horizontal dimensions of the mold bore 11 to thereby seal the mold
when molten metal is introduced therein. The bottom block 13 is
slidably mounted on a smaller supporting member 14 which is affixed
to the shaft 15. Shaft 15 is suitably supported on withdrawal or
support table 16. Retainer means 17, preferably having an L-shaped
cross section, is affixed to the bottom block 13 to loosely lock
the bottom block to the supporting member 14 but allowing for
substantial horizontal movement between the bottom block and the
supporting member. The spaces 18 between the support member 14 and
the vertical surfaces of the retaining means 17 allow for
horizontal movement of the bottom block. A movement of from about
0.3 to 3 inches, depending upon mold size, is adequate for
self-centering characteristics. Guide means 19 are provided on the
outer vertical surfaces of the assembly 10, for example, on
retaining means 17. Preferably, three or more guide means 19 are
provided around the periphery of the assembly. Although the guide
means 19 are shown in the drawings as buttons, the extensions may
be rollers or a projecting ridge around the periphery of the
retaining means. A plurality of vertically disposed guide runs 20
are positioned in a fixed spatial relationship with respect to the
bore 11 of the mold 12 and are adapted to guide the bottom block
assembly 10 into the mold bore 11 by means of the guide extensions
19. As shown in the drawing, the guide runs 20 are preferably
flared outward in the downward direction to provide for the smooth
insertion of the bottom block assembly into the mold bore. To allow
for the insertion of the bottom block into the mold, the guide
surfaces are positioned no closer than the projected perimeter of
the mold bore. Preferably, the guide runs 20 are made integral with
the mold assembly 12, for example, as a concentric tubular
extension of the water jacket.
The materials of construction for the assembly can be of any
suitable materials, such as low-carbon steel, aluminum and the
like. Preferably, one or both of the contact surfaces between the
bottom block and the supporting surfaces are provided with a
bearing material, such as bronze and the like. To facilitate
movement of the bottom block, preferably the horizontal contact
surfaces are smoothed by machining or the like.
Prior to casting, the bottom block assembly 10 is raised into
position within the mold bore 11. The guide extensions 19 ride the
vertically disposed guide runs 20 aligning the bottom block
assembly with respect to the mold bore and thereby preventing any
contact between the bottom block assembly 10 and the mold surfaces.
Molten metal is then introduced into the mold bore by suitable
means (not shown) and immediately the molten metal begins to
solidify. When sufficient solidification has occurred, the bottom
block assembly is slowly lowered by lowering the support table 16.
As the ingot emerges from the mold, it is flooded with coolant from
sprays 24 to further cool the ingot and to cause substantial
solidification of the molten metal above the solidified portion of
the ingot. The guide runs 20 and guide extensions 19 insure that as
the bottom block is removed from the mold bore, no contact is made
therewith by the bottom block.
Although only one mold assembly and bottom block assembly are shown
in the drawings, in commercial practice, a plurality of molds and
associated bottom block assemblies are employed at each casting
station. The withdrawal table or platen 16 which is hydraulically
operated for vertical movement will normally support a plurality of
bottom block assemblies. Thus, the drop rate for each ingot is the
same and the resultant metallurgical structure and surface
characteristics of all of the ingots will be approximately the
same.
In FIGS. 2 and 3, another embodiment of the invention is
illustrated. The bottom block assembly is provided with means which
lock the ingot into position with the bottom block during the
initial solidification of the ingot but which readily disengages
the ingot when the ingot is removed from the pit by conventional
means. The bottom block and supporting surface are essentially the
same as shown in FIG. 1. The retaining means 17 are essentially two
or more semicircular or arcuate members preferably of L-shaped
cross section which are affixed to the bottom block 13 and which
generally lock the bottom block 13 in a loose manner to the
supporting member 14 as previously discussed. Lock links 30 are
situated in vertical recesses in the periphery of the assembly and
are rotatably mounted therein by means of rod 31 which is affixed
to the retaining means 17 or an extension of the bottom block. The
upper portion 32 of said lock links 30 extend above and over the
upper surface of the bottom block 13. The end of the inwardly
extending portion of the lock link is provided with a vertical
surface 33 which is inclined in the direction of the bottom block
away from the axis of the bottom block. The surface 33 is inclined
sufficiently to insure contact with the shrinking ingot as it
solidifies. Means 35 are provided to urge the upper portion 32 of
the lock link 30 to rotate into engagement with the bottom block
13. The urging means must exert enough force to prevent
disengagement of the lock link 30 with the solidifying ingot when
the ingot is being urged out of the mold but also allow the ingot
to be easily removed after the ingot is cast. A suitable means is
shown in the drawing as a spring 36 which is positioned in the
recess 37 in the lock link and recess 38 of member 39 to urge the
lock link into engagement with the bottom block. Member 39 is
suitably supported, for example, to support member 14.
As the molten metal begins to solidify during the initial periods
of the casting operation, the inclined surfaces 33 of the lock link
30 insure contact with the shrinking metal. As the bottom block is
lowered, the lock link mechanisms urge the forming ingot out of the
mold. When the ingot is completely cast, it is readily disengaged
from the bottom block assembly by the conventional ingot removal
means without damage to the bottom block.
Although the invention has been described in terms of casting
apparatus for casting circular ingots, the present invention is
fully applicable to ingots of any shape. Moreover, it is obvious
that various modifications and improvements can be made to the
invention without departing from the spirit thereof and the scope
of the appended claims.
* * * * *