U.S. patent number 3,848,658 [Application Number 05/342,096] was granted by the patent office on 1974-11-19 for carriage orientation and lift system for a twin belt continuous metal casting machine.
This patent grant is currently assigned to Hazelett-Strip-Casting Corporation. Invention is credited to Robert J. Carmichael, Robert William Hazelett, John Frederick Barry Wood.
United States Patent |
3,848,658 |
Hazelett , et al. |
November 19, 1974 |
CARRIAGE ORIENTATION AND LIFT SYSTEM FOR A TWIN BELT CONTINUOUS
METAL CASTING MACHINE
Abstract
A carriage orientation and lift system are described for a
continuous metal casting machine of the twinbelt type in which a
virtual parallelogram lift mechanism raises or lowers the upper
carriage while maintaining it parallel with the lower carriage.
This lift system permits the lower carriage to be rigidly attached
to the main chassis frame and back of the machine with a lever lift
arm extending over the back to support the upper carriage, this arm
being mounted on the back by a fulcrum pivot assembly including
adjustment means to align the motion of the upper belt with the
lower belt so that they "track" each other precisely along the
upper and lower surfaces of the casting region. A follower roller
engages an upright curved cylindrical segment on the back of the
machine, and the radius of this curved segment plus the radius of
the follower roller is equal to the length of the lift arm between
the fulcrum and the pivot connection to the upper carriage to
provide parellelism of the carriages at all lifted positions. A
downstream shift assembly at this pivot connection enables the
upper carriage to be shifted upstream or downstream for injection
or open pool feeding of the molten metal input to the machine, and
the curved cylindrical segment and follower roller facilitate such
adjustment, this downstream adjustment being completely independent
of the upper carriage lift means and lifting action.
Inventors: |
Hazelett; Robert William
(Winooski, VT), Wood; John Frederick Barry (Burlington,
VT), Carmichael; Robert J. (Colchester, VT) |
Assignee: |
Hazelett-Strip-Casting
Corporation (Malletts Bay, Winooski, VT)
|
Family
ID: |
23340310 |
Appl.
No.: |
05/342,096 |
Filed: |
March 16, 1973 |
Current U.S.
Class: |
164/432 |
Current CPC
Class: |
B22D
11/0677 (20130101) |
Current International
Class: |
B22D
11/06 (20060101); B22d 011/06 () |
Field of
Search: |
;164/87,88,154,278,283R,283S |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Juhasz; Andrew R.
Assistant Examiner: Brown; John S.
Attorney, Agent or Firm: Bryan, Parmelee, Johnson &
Bollinger
Claims
We claim:
1. A carriage orientation and lift system for a twin-belt
continuous metal casting machine comprising:
a machine frame including a chassis with a back frame extending
upwardly therefrom,
a lower belt carriage extending outboard from this chassis in rigid
cantilevered relationship adapted to have a lower casting belt
revolved around it,
a fulcrum pivot on said back frame above the level of said lower
carriage,
a lift arm pivotally attached to said back frame by said fulcrum
pivot, said lift arm having a rear portion extending behind said
back frame and a front portion extending in front of said back
frame,
lift means connected to the rear portion of said lift arm and to
the frame for pulling downwardly on the rear portion of said lift
arm to swing up the front portion thereof,
an upper carriage connected by a pivot assembly to the front
portion of said lift arm, said upper carriage being positioned
above said lower carriage and being adapted to have an upper
casting belt revolved around it in parallel relationship with said
lower belt,
a convex circularly curved cylindrical segment positioned on said
back frame at a lower level than said fulcrum pivot,
roller means mounted on said upper carriage at a lower level than
said pivot assembly in rolling engagement with said curved
cylindrical segment,
the axis of said curved cylindrical segment being parallel with the
axis of said pivot assembly and also parallel with the axis of said
fulcrum pivot,
the distance from said fulcrum pivot to the axis of said curved
cylindrical segment being equal to the distance from the axis of
said pivot assembly to the axis of said roller means, and
the effective radius of curvature of said curved cylindrical
segment plus the radius of said roller means being equal to the
distance between the axis of said fulcrum pivot and the axis of
said pivot assembly,
thereby to maintain the upper carriage parallel with the lower
carriage as the upper carriage is raised and lowered by said lift
arm.
2. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which
said upper carriage has an L-shaped structure as seen in cross
section formed by an upright frame portion connected by said pivot
assembly to said lift arm and an outboard extending cantilevered
portion around which said upper belt is revolved, with said roller
means being mounted on said upper carriage near the elbow of said
L-shaped structure.
3. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which
said pivot assembly connecting the upper carriage to the forward
portion of said lift arm includes means for shifting the upper
carriage in the upstream and downstream direction parallel with the
axis of said pivot assembly, and said curved cylindrical segment
extends upstream and downstream along said back frame sufficiently
for it to be engaged by said roller means at all upstream and
downstream shifted positions of said upper carriage.
4. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 3, in which
said pivot assembly includes first, second and third axially spaced
hanger members on the forward portion of said lift arm, a tubular
member slidably mounted in said hanger members, a pair of axially
spaced support members secured to said upper carriage, one of said
support members being secured to said tubular member between the
first and second hanger member and the other of said support
members being secured to said tubular member between the second and
third hanger member for providing firm support for the upper
carriage at all of its shifted positions.
5. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which a
tangent plane to said convex circularly curved cylindrical segment
near the center of the operating range of said roller means extends
vertically, whereby a relatively large amount of lift of the upper
carriage is provided with a minimum amount of lateral displacement
thereof.
6. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which
said fulcrum pivot comprises two pivot assemblies at the upstream
and downstream side of said lift arm, each of said pivot assemblies
including a pivot pin projecting out from the side of said lift
arm, a pair of upstanding support members on the upstream and
downstream side of said back frame, respectively, and an eccentric
bushing mounted in each of said support members, said eccentric
bushings each being rotatable about the pivot pin and lockable in
different positions for adjusting the lift arm to adjust the
upstream and downstream ends of said upper carriage vertically and
laterally to align the upper belt to track along the casting region
precisely parallel with the lower belt, thereby to avoid lateral
creeping movement between the belts and metal section being
cast.
7. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which a
platform extends rearwardly from said chassis frame in cantilevered
relationship therefrom, and the drive mechanism for revolving the
belts on said carriages is mounted on said platform.
8. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, including a
base support unit having a pair of spaced parallel beams extending
outboard beneath the lower carriage and a base frame extending
between said beams and positioned beneath said main chassis frame,
said main chassis frame being pivotally connected to said base
frame at the downstream end of said machine by a front and rear
pivot which are axially aligned, and means for adjusting the
elevation of the upstream end of said main chassis frame.
9. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 8, including
hold down clamp means for pre-loading the chassis frame down
against the base frame at said rear pivot.
10. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which an
upwardly extending safety link is pivotally connected to the front
of the upstanding back frame, said safety link being swingable
forward into an extended position, said upper carriage has a ledge
on its inboard side under which the extended safety link can be
engaged when said carriage is in its raised position, and said
ledge extending upstream and downstream a sufficient distance to be
engageable by the extended safety link regardless of whether the
upper carriage is in its upstream or downstream position.
11. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 5, in which
said lift arm extends generally horizontally in the mid-range of
its lift travel and said lift means act downwardly and forwardly on
the rear portion of said lift arm to provide an approximately
constant mechanical advantage throughout the range of lift
operation, whereby a substantially constant fluid pressure can be
used in said lift cylinder means throughout said range of
operation.
12. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 5, in which
the hardness of the curved surface of said curved cylindrical
segment is less than the hardness of the roller means engaged
thereagainst.
13. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, in which a
belt treatment unit extends across the upper carriage from its
inboard side to its outboard side, latch means on the outboard side
of said treatment unit for latching said unit to the upper carriage
in operating position, a tension member connected to the front end
of said lift arm above the level of said pivot assembly and being
connected to said latch means, whereby the initial part of the
upward swing of the front portion of said lift arm will pull said
tension member to unlatch said latch means, and the farther upward
swing of said lift arm will pull said tension member farther to
swing said treatment unit up away from the upper carriage.
14. A carriage orientation and lift system for a twin-belt
continuous metal casting machine as claimed in claim 1, including a
base support unit having a pair of spaced parallel beams extending
outboard beneath the lower carriage and a base frame extending
between said beams and positioned beneath said main chassis frame,
each of said beams having a foot pad beneath its outboard end
engageable with the ground, and said base frame having a third foot
pad located beneath it intermediate said beams and engageable with
the ground, whereby the machine as a whole has a three point
support.
15. A carriage orientation and lift system for a twin-belt
continuous metal casting machine comprising:
a machine frame including a chassis with a back frame extending
upwardly therefrom,
a lower belt carriage extending outboard from this chassis in rigid
cantilevered relationship adapted to have a lower casting belt
revolved around it,
fulcrum pivot means mounted on said back frame above the level of
said lower carriage,
a lift arm pivotally attached to said back frame by said fulcrum
pivot means, said lift arm having a rear portion extending behind
said back frame and a front portion extending in front of said back
frame,
lift means connected to the rear portion of said lift arm and to
the frame for pulling downwardly on the rear portion of said lift
arm to swing up the front portion thereof,
an upper carriage connected by a pivot assembly to the front
portion of said lift arm, said upper carriage being positioned
above said lower carriage and being adapted to have an upper
casting belt revolved around it in parallel relationship with said
lower belt,
a convex cylindrical member positioned on said back frame at a
lower level than said fulcrum pivot,
roller means mounted on said upper carriage at a lower level than
said pivot assembly in rolling engagement with said cylindrical
member,
said cylindrical member extending parallel with the axis of said
pivot assembly and also parallel with said fulcrum pivot means,
and
said fulcrum pivot means comprising two axially aligned spaced
pivot mechanisms, at least one of said pivot mechanisms including
adjustment means for slightly shifting the effective position of
one of said pivot mechanisms relative to the other pivot
mechanism,
thereby slightly to shift the orientation of the lift arm and upper
carriage with respect to the lower carriage for tracking the
movement of the upper belt with respect to the lower belt along the
top and bottom of the casting region defined between said belts to
avoid lateral creeping movement of the belts with respect to the
product being cast between them.
Description
DESCRIPTION
The present invention relates to a carriage orientation and lift
system for a twin-belt continuous metal casting machine. Such a
twin-belt casting machine uses a pair of thin, wide endless metal
belts to define the upper and lower casting surfaces of the casting
region. These belts are revolved around cantilevered upper and
lower carriages. Separation of these carriages is necessary from
time to time to replace these casting belts, or to change the edge
dams and provide access for servicing the carriages and rolls and
to make periodic inspections.
There have been earlier twin-belt continuous metal casting
machines, for example, as shown in U.S. Pat. Nos. 2,640,235;
2,904,860; 3,036,348; 3,041,686; 3,123,874; 3,142,873; 3,167,830;
3,228,072; and 3,310,849. As time has passed, the operating
requirements for these twin-belt casting machines have become
progressively more demanding because it is desired that larger and
larger cast sections be produced with great accuracy. Thus, much
larger amounts of molten metal are now desired to be fed into the
machine per minute of operation.
Among the many advantages of the present invention are those
resulting from the fact that very wide, large casting belt
carriages can be positioned in precise parallel relationship with
respect to each other, and the upper carriage can be raised a
substantial distance while maintaining the parallelism desired. A
virtual parallelogram lift system that raises the upper carriage is
provided to accomplish the desired separation of the carriages, and
also it permits rigidly attaching the lower carriage to the main
chassis frame without complication or conflict with other
functions. A follower roller engages against an upright, curved
cylindrical segment on the back of the machine and the radius of
curvature of this curved segment plus the radius of the follower
roller is equal to the length of the lift arm between the fulcrum
and the pivot connection to the upper carriage. Thus, parallelism
is maintained without the complexity of a fourth movable link and
associated pivots. A substantial amount of vertical lift is thereby
provided for the installation and removal of large casting belts on
machines with large mold dimensions. For example, the illustrated
embodiment is designed to provide a casting mold space "C" which
may be as wide as up to 100 inches and may be as long as up to 116
inches or more, with the belts being somewhat larger than these
dimensions.
Substantial vertical lift of the upper carriage also facilitates
the changing of casting belts, edge dams, tundish, nosepiece and
nozzle assemblies on various sizes of casting machines in
installations where "down time" is critical and changes in casting
dimensions are frequent. A large opening between the carriages
produced by fully raising the upper carriage provides for maximum
convenience and accessibility for necessary inspection, maintenance
and repair functions.
When the illustrated casting machine is in operation, the upper
carriage is supported by resting upon gauge spacers which attach to
the lower carriage and very accurately determine the thickness of
the cast section. These spacers are accurately machined blocks that
provide vertical support for the upper carriage, and control the
distance between the two carriages.
Accordingly, another important advantage of the lift system
embodying this invention is that the upper carriage and
corresponding casting surface remain parallel with the lower
carriage while being raised or lowered. This facilitates the
changing of selected casting thickness together with corresponding
edge dams and gauge spacers. Maintaining the upper carriage
parallel to the lower carriage during operation of the lift
function also allows the upper carriage to be used to position
tundish, nosepiece or core assemblies. Desirably, a lift system
embodying the present invention that maintains the constant
parallel position of the upper carriage can be used as well to
actuate the head latch and raise the leveler or other auxiliary
assemblies when the lift system is operated.
In certain prior twin-belt machines, it has been desirable to
isolate the lower carriage from the base frame. For example, U.S.
Pat. No. 3,142,873 shows a system for isolating the lower carriage
from the base frame. Thus, any distortion of the base due to
unexpected loads or foundation problems did not distort the lower
carriage. In a machine embodying the present invention the lower
carriage is rigidly attached to a main chassis which is pivoted to
the base frame but this chassis also carries a heavy upright box
frame forming the whole back of the machine so that the back frame
of the machine, the main chassis, and the lower carriage are
rigidly interconnected to provide great strength and rigidity.
It is a further advantage of a machine embodying the present
invention that adjustment means are provided at the fulcrum of the
virtual parallelogram lift system to align the upper and lower
carriages so that the direction of travel of the two belts is
exactly parallel along the top and bottom surfaces of the casting
region C. This precise parallelism, i.e. "tracking" of the two
belts, is required to assure that there is no lateral creeping
movement between either of the belts and the section of molten
metal being cast. Such lateral creeping movement if it occurs can
drastically reduce the life of the casting belt coating and produce
flaws in the surface finish of the cast section. The virtual
parallelogram lift system eliminates a link and two pivots, thus
providing additional space for other functions. In addition, the
absence of such a link and associated pivots enables the adjustment
means at the fulcrum of the lift arm to produce tracking of the two
belts without further links or pivots to be adjusted.
For optimum flexibility in use, the area above the upper carriage
is desirably open so that auxiliary equipment such as belt drying
or coating apparatus can be mounted there. To provide for both
injection and open pool feeding of the molten metal, a means for
shifting the upper carriage in the direction of travel of casting
is provided. For open pool feeding the upper carriage is shifted
downstream a substantial distance. This shift function is
independent of all other machine operations. The virtual
parallelogram lift system facilitates this downstream shifting by
eliminating pivots which might otherwise require shifting. The
curved segment against which the follower roller rests is much
wider than the roller thereby accommodating all downstream shifts
of the upper carriage.
A positive safety link is provided to positively lock and hold the
upper carriage in the raised position to prevent its inadvertent
dropping in the event of loss of fluid pressure in the lift
cylinders. The safety link is located behind the carriages, away
from the working area of the machine. The lift system illustrated
herein is adapted to function smoothly and the vertical position of
the top carriage can be easily controlled.
The various features, aspects and advantages of the present
invention will be more fully understood from a consideration of the
following description of a twin-belt continuous metal casting
machine incorporating the invention, considered in conjunction with
the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the input or upstream end of a
continuous strip-casting machine embodying the present invention,
as seen looking toward the machine from a position in front and
beyond the outboard side of the two belt carriages;
FIG. 2 is an elevational view of the machine as seen looking toward
the outboard sides of the two belt carriages;
FIG. 3 is an elevational view of the machine as seen looking toward
the back of the support frame at the inboard side of the
machine;
FIG. 4 is an elevational view looking toward the input or upstream
end of the continuous casting machine;
FIG. 5 is a cross-sectional view, taken along the line 5--5 of FIG.
2, looking toward the right;
FIG. 6 is a schematic diagram illustrating the virtual
parallelogram linkage provided by the lift system in the machine of
the present invention;
FIG. 7 is a perspective view of the upper carriage shift
system;
FIG. 8 is an enlarged sectional view of the roller and mount, being
taken along line 8--8 of FIG. 4; and
FIG. 9 is an enlarged sectional view of the lift arm bearing and
mounting assembly, being taken along line 9--9 in FIG. 4.
DETAILED DESCRIPTION
In the continuous casting machine 10, which is shown in the
drawings as an illustrative example of the present invention,
molten metal is fed into the upstream end or input of the machine
between upper and lower endless, flexible casting belts 12 and 14.
The molten metal is solidified in a casting region C (FIGS. 2 and
5) defined by the spaced parallel surfaces of the upper and lower
casting belts 12 and 14.
The two casting belts 12 and 14 are supported and driven by means
of upper and lower belt carriages which are indicated in FIGS. 1, 2
and 4 at U and L, respectively. The upper carriage includes two
main rolls 16 and 18 (FIG. 2) around which the casting belt 12 is
revolved as indicated by the arrows. The roll 16 near the input end
of the machine is referred to as the upstream roll and the other
roll 18 is called the downstream roll. Similarly, the lower
carriage L includes main upstream and downstream rolls 20 and 22
around which the lower casting belt 14 is revolved.
The lower carriage L projects from a chassis 24 (FIGS. 2 and 4)
which is adapted to be tilted to various casting angles. In order
to provide for the adjustable tilting of this chassis 24, it is
attached to the base 26 of the machine by a three-point support
system that includes two pivot connections and an adjusting link
27. The two pivot connections 28 and 30 are located toward the
downstream end of the machine, and the adjusting link 27 is near
the upstream end. This link is secured by pivots 31 and 32 and can
be removed and replaced by a longer link when it is desired to
increase the inclination, and vice versa.
As shown in FIGS. 1, 2 and 3, the base 26 and a pair of spaced
horizontally extending parallel base beams 34 and 36 bolt together
to form an integral, horizontal support unit B for the remainder of
the machine. This support B is generally U-shaped in plan, with the
two base beams 34 and 36 extending in an outboard direction beneath
the lower carriage L. The chassis frame 24 is attached to the base
26 by the pivot system discussed above that allows the carriages U
and L to be tilted to any casting angle and still remain in
alignment with the base 26. This chassis frame 24 forms the main
chassis of the machine proper as distinguished from the support
unit B at the base.
A rigid upstanding box frame back 38 is securely bolted to the
upper surface of the chassis 24. This box frame back 38 provides
the upright back of the machine, and at its upper end there are two
upstanding lift arm support members 41 and 43 which support a lift
arm 40 at its fulcrum point 42 (FIG. 5) by means of pivot pin
assemblies. As shown in FIG. 5, this box frame back 38 includes
vertical front and back plates 44 and 45 with horizontal stiffeners
46 between them and a pair of vertical end plates 47 and 48 (FIGS.
2 and 3) to which the upstanding lift arm support members 41 and 43
are secured. The lift arm 40 is swung up and down by the action of
the two fluid power cylinders 50 and 51 whose piston rods 52 are
pivotally attached at 53 to brackets 54 secured to the rear plate
45 of the box frame back 38. The cylinders 50 and 51 have trunnions
55 pivotally mounted in the rearwardly extending end members 56 of
the lift arm 40. The upper carriage U is pivotally attached to the
front end of the lift arm 40 by the downstream shift assembly 61,
which is located at the outboard end of the lift arm 40.
This lift arm is strongly built to have a thicker section near the
fulcrum pivot 42 tapering toward its ends, and it includes a top
plate 57 secured to bottom plates 58 and 59 by vertical webs
between them, as seen in FIG. 5.
In order to raise and lower the upper carriage U while controlling
its orientation to remain parallel with the lower carriage L, a
virtual parallelogram lift system 60 has been devised as shown most
clearly in FIGS. 5 and 6. The box frame back 38 of the machine
forms one link 1 of the parallelogram pivoted at 42 to a central
portion of the lift arm 40, and the front portion of this lift arm
forms a second link 2. The upper carriage U includes an inboard
vertical frame structure 62 which depends from the pivot shift
assembly 61, and then as shown generally at 63 in FIG. 6 the belt
supporting portion is cantilevered from the upright portion 62.
Thus, as seen in cross section in FIGS. 5 and 6, the upper carriage
has an L-shape or dog-leg shape.
The third link 3 is formed by the upright dog-leg portion 62 of the
upper carriage on which bracket members 66, 67 (FIG. 8) and roller
65 are mounted.
The fourth link 4 is a virtual one as indicated dashed in FIG. 6
with the other two pivots X and Y being virtual pivots. These are
called virtual pivots because there is no actual pivot connection
between a pair of links at the pivot points X and Y. This virtual
fourth link and pivots X and Y are provided by a convex circularly
curved cylindrical segment 64 bolted to the front plate of the
upright box frame back 38 and a follower roller 65 attached by
mounting bracket members 66 and 67 (FIG. 8) to the inboard side
plate 68 of the vertical frame structure 62 of the upper carriage.
The roller 65 is mounted on the upper carriage U near the elbow of
its L-shaped frame structure formed by the upright frame portion 62
and cantilevered belt supporting portion 63.
The radius of the convex curved cylindrical segment 64 plus the
radius of the roller 65 are equal to the distance between the axes
of the pivots 42 and 61 in the front portion of the lift arm, i.e.,
equal to the length of the upper link 2. The axis, i.e. center of
curvature, of the cylindrical segment 64 is located at the virtual
pivot X and extends parallel with the axis of the pivot assembly 61
and also parallel with the axis of the fulcrum pivot 42 which is
also parallel to the pivot assembly 61. In addition, the distance
from the axis X to the axis of the pivot 42 (which is the length of
the link 1) is equal to the distance between the axis Y of the
roller 65 and the axis of the pivot 61 (which is the length of the
link 3).
Although an exactly circular cylindrical curved segment 64 is
shown, it is to be understood that it is possible to use a segment
64 having a surface which approximates this desired shape in order
to save machining costs. The reason such an approximation is
possible is that the upper carriage rests upon gauge blocks on the
lower carriage which control its final precise position when it is
fully lowered into operating position with respect to the lower
carriage. Accordingly, the "circularly curved cylindrical segment"
is to be interpreted to include approximations thereof.
As mentioned above, the upper carriage U has an L-shaped
cantilevered structure 63 carried by the upright dog-leg portion
62, and the weight of this upper carriage when lifted is supported
by the pivot assembly connection 61 with the lift arm 40 and whose
orientation about this pivot 61 is controlled by the action of the
roller 65 and cylindrical segment 64. As the upper carriage U is
raised or lowered, the center line (axis) of its pivot 61 with the
lift arm 40 travels in a circular path V about the axis of the lift
arm fulcrum pivot 42. In order for the upper carriage U to remain
parallel with the lower carriage L, the center line of the foller
65 is arranged to travel in an identical arc W, and this is
accomplished by making the radius of the cylindrical segment 64
plus the radius of the roller 65 equal to the length of the link
2.
During operation of the lift system, the roller 65 is under a
compressive load and follows the precisely curved machined surface
of the segment 64, thus producing the desired parallelogram motion.
It is the side portion of the arc W which is used which enables a
large amount of vertical movement to be obtained with little
horizontal displacement of the upper carriage U. In other words, as
shown in FIG. 4, a tangent plane 70 (shown dash and dotted) to the
curved cylindrical segment 64 near the center of the operating
range extends vertically.
In order to position the curved segment 64 precisely on the
vertical front plate 44, there is a horizontal locator bar 72 (FIG.
4) which extends across beneath the bottom end of the curved
segment 64, i.e. serving as a ledger. Cap screws (not shown) retain
the ledger bar 72 in position on the front surface of the upright
box frame back 38. This bar 72 also facilitates the positioning of
plate 73 behind the segment 64 both of which are securely fastened
to the box frame 38 by cap screws. This spacer plate 73 is mounted
between the segment 64 and the box frame back 38 and can be
machined to correct any minor misalignment, thus assuring proper
contact at all operating positions between the segment 64 and the
roller 65. The curved segment is wide enough so that there is full
contact with the roller 65 for all downstream shift positions of
the upper carriage U, even including the maximum amount of
downstream shift of this upper carriage. The hardness of the curved
surface of the segment 64 is somewhat less than that of the roller
65 to produce ideal operating conditions at the point of contact.
Also, this relative hardness accommodates manufacturing tolerances
and adjustments in orientation of the upper carriage.
The roller 65 (FIG. 8) is the outer portion of an anti-friction
bearing whose inner race 74 is retained between bracket members 66
and 67 by retainers 75 which are compressed between a shoulder 76
on one end of the bearing pin 77 and a bushing 78, a lock washer 79
and lock nut 80 screwed on the opposite end of the pin 77. The
bearing for roller 65 includes anti-friction elements 81 and is
sealed against the ingress of liquid coolant and foreign material
on both sides by "0" rings 82 which ride in a groove in the
periphery of each retainer 75 and run against the inside surface of
the outer race of the bearing which forms the roller 65. This
bearing 65, 81, 74 can be lubricated through a passage 82 bored in
the retaining pin 77. To insure proper tracking and that there is
no lateral motion between the roller 65 and the segment 64, a key
84 (FIG. 5) is used to accurately locate the bracket members 66 and
67 on the inboard side plate 68 of the top carriage. The bracket
members 66 and 67 are securely fastened to the side plate with cap
screws. This roller means is used to withstand the high operating
loads and adverse operating conditions of liquid coolant, heat and
fumes encountered during metal casting. In some cases, particularly
for a long machine, more than one roller 65 may be utilized in
axial alignment with each other engaging the curved surface 64.
The force required to raise the top carriage U is produced by the
action of the two fluid power cylinders 50 and 51. As fluid
pressure is applied to the rod end of these cylinders, the piston
rods 52 are retracted causing a downward force F (FIG. 6) on the
rear members 56 of the lift arm 40, thereby swinging the front
portion of the lift arm 40 up about its fulcrum pivot 42 thus
raising the upper carriage U.
Although fluid powered lift cylinders 50 and 51, such as
hydraulically activated lift cylinders, are shown as the lift means
to exert a downward force on the rear portion of the lift arm 40 by
acting between the pivots 53 and 55 (FIGS. 4 and 5), it is to be
understood that other lift means can be used. For example, screw
jacks can be employed effectively acting between the pivots 53 and
55 with these screw jacks being actuated by electric or hydraulic
motors or manually actuatable.
By virture of the provision of the virtual parallelogram described
above, the need for an actual link 4 and pivots X and Y is removed,
thus there is more room available in the box frame back 38 for
other equipment. Also, the elimination of pivots X and Y avoids
lubrication and multiple bearing sealing problems.
The lift arm 40 is supported on each side by a fulcrum pivot pin 42
(FIG. 9) about which rotates a bushing 86. This bushing is retained
in the box frame back 38 of the machine by a thrust washer 87 and
cap 88. An advantage of this rearwardly extending level type lift
system 60 is that it can be mounted on the upper portion of the
rigid box frame back 38 with the lift arm extending over the top of
the box frame back 38. Thus, the top positioned lift arm 40 does
not limit the space required for other functions, and the location
of the lift means 50 and 51 behind the box frame back 38 enable the
lift arm and lift means to withstand adverse operating conditions.
This lift system allows the lift means 50 and 51 to be mounted on
the back of the machine thus providing more space in the working
area and a better environment for the lift cylinders because they
are more remote from the molten metal in the casting region C and
are remote from the liquid coolant being applied to the reverse
surfaces of the belts along the casting region.
The lift arm arrangement as shown in FIG. 5 in which the line of
action of the lift means 50 and 51; that is, the line passing
through the axes of the pivot points 55 and 53 is approximately
perpendicular to the line passing through the pivot points 42 and
53 provides a relatively constant mechanical advantage for the lift
cylinders throughout the range of lift operation. This relatively
constant mechanical advantage results in substantially constant
hydraulic pressure requirements throughout the range of lift. Due
to the very limited degree of associated frictional forces, the
operation of the lift system is smooth and readily controllable
during all phases of the lift cycle. Also, the space above the
upper carriage is free of obstruction and can be used to
accommodate other mechanism such as the belt treatment unit 85.
In addition to providing support for the lift arm 40, the pivot pin
assembly shown in FIG. 9 can be used to adjust the orientation of
the lift arm, so that the direction of travel of the top and bottom
casting belts is exactly parallel. This is accomplished by the
rotation of the bushings 86 which are eccentric in structure. Each
cap 88 axially retains the thrust washer 87, bushing 86 and lift
arm 40 in position on top of the box frame back 38. The cap 88 is
fastened to the vertical members 41 and 43 of the box frame back by
cap screws 92 and a lock bolt 90 prevents rotation of the eccentric
bushing 86. This eccentric bushing can be rotated in either
direction by increments of five degrees, thus providing both
horizontal and vertical adjustment of the upper carriage at both
its upstream and downstream ends.
There are eight pre-drilled apertures 89 spaced uniformly around
the axis of the cap 88, and nine uniformly spaced sockets are
pre-drilled in the end face of the bushing 86. Thus, there are a
total of 72 possible combinations of apertures 89 and sockets 83
into which the lock bolt 90 can be inserted, hence providing five
degree increments of adjustment. The spherical outer surface S
(FIG. 9) of each thrust washer 87 accommodates this adjustable
orientation of the upper carriage in any direction at both the
upstream and downstream fulcrum pivots 42.
In this way, the upper carriage is adjusted to cause its belt to
"track" exactly parallel with the lower belt along the top and
bottom of the casting region C; so that the lateral creeping
movement of the belts with respect to the cast product is avoided.
This true tracking of the belts reduces abrasion on the coated
casting surfaces of the belts 12 and 14 and avoids flaws in the
surface finish of the cast section. The fulcrum pivot pins 42 and
eccentric bushings 86 can be lubricated through the port 91
provided in their respective caps 88 and thrust washers 87. If
desired, either or both of the eccentric bushings 86 can
conveniently be removed and replaced by one having greater or
lesser eccentricity if needed to make a more precise alignment
adjustment shown between the upper and lower carriages.
The top carriage U is pivoted on the front portion of the lift arm
40 by the downstream shift assembly 61 and can be moved a maximum
of twelve inches independently of all other functions of the
casting machine 10. This movement is desirable to allow molten
metal to be distributed into the casting region C by either the
open pool or injection method.
The main component of the downstream shift assembly 61 is a tube 94
that slides in three bushings 95 that are retained respectively in
three spaced hanger members 93 on the front portion of the lift arm
40 by means of snap rings 96. The vertical arm structure 62 of the
upper carriage U includes a pair of spaced end plate support
members 97 that are rigidly attached to this tube 94 by two rings
98 and a split ring 99. The upstream support member 97 is
positioned intermediate the first and second hanger members 93,
while the downstream support member 97 is positioned intermediate
the second and third hanger members 93 Accordingly, rigid support
is provided for the upper carriage regardless of whether it is
shifted upstream, downstream or in-between.
In order to move the main slidable tube 94, there is a larger
diameter tubular housing 100 and a spacer 101 bolted to the
upstream hanger member 93 of the lift arm 40 concentrically with
the main tube 94. A cap 102 is securely fastened to the end of this
housing 100 by cap screws. A thrust shaft 104 having screw threads
105 is axially retained in this cap 102 by the action of a pair of
thrust bearings 106, spacers 107, lock washer 108 and lock nut 110.
The end of this shaft 104 is threaded and screws into a cap 112
which is securely fastened to the end of the main tube 94. When the
thrust shaft 104 is turned by applying a wrench to the head end
114, the assembly operates like a screw jack and shifts the top
carriage U upstream or downstream with relation to the lift arm 40
and the machine.
The lift system 60 is provided with a positive safety link 116
(FIG. 5) that will retain the upper carriage in the fully raised
position. This safety link 116 is manually operable, can be locked
in either extended or retracted position, and can be used for all
downstream shift positions of the top carriage. While in use,
holding up the carriage U, the safety link 116 is in extended
position under a compressive load, between a ledge 117 on the top
carriage and the pivot 118 of the link 116. In addition, as a back
up to the pivot 118, there is a load-carrying ledge 120 at the
front of the box frame back 38. The bottom end of the pivoted
safety link rests on the safety ledge 120 when the link is swung
out to its extended position, so as to catch under the carriage
ledge 117. The safety link 116 is located so that it does not
interfere with the changing of the casting belts, or any other
required maintenance work.
As seen in FIG. 5, there are a pair of edge dams 121 and 122 which
serve to define the edges of the casting region C. These edge dams
are flexible and revolve around the lower carriage, as seen in FIG.
2. They can be removed and replaced by thicker or thinner ones
depending upon the section of metal being cast. These edge dams 121
and 122 and also the casting belts 12 and 14 can be changed when
the upper carriage is raised as indicated by the dashed and dotted
outline in FIG. 5. Also, inspection and servicing of the machine
can be conveniently performed when the upper carriage is raised. It
is at these times that the safety link 116 is extended to make sure
that the upper carriage does not inadvertently come down. The lift
system 60 shown is designed to provide 20 inches of lift for the
upper carriage U.
As further provision for controlling carriage orientation, it is
noted that the back downstream carriage pivot 30 (FIG. 3) has an
associated hold-down clamp including a curved saddle 124 extending
over the pivot pin 30 with a clamp bolt 126 and a nut 127. This
clamp bolt extends down through an anchoring bracket 129 on the
main chassis frame 24 and through the saddle 124 and pivot 30 for
securely locking the pivot 30 to remove all tolerance in the pivot.
In this way the main chassis frame is pre-loaded (as seen in FIG.
3) down against the base at the downstream back pivot point to
prevent any slight movement there.
In addition, the pivot brackets 54 for the lift cylinder piston
rods are located on the back frame 38 by keys 128 (FIGS. 4 and 5)
in a keyway 130 (FIG. 3) to assure precise alignment.
The belt drive mechanism 132 is mounted upon a platform 134 which
is cantilevered from the back of the main chassis 24. Thus, this
drive mechanism is positioned in a more favorable environmental
position than if it were closer to the casting region. Also, the
cantilevered platform 134 and drive 132 somewhat counterbalance the
lower carriage L which is rigidly cantilevered from the front of
the main chassis 24 with the upper carriage U above it.
As mentioned previously, there is a belt treatment unit 85 (FIGS.
1, 2 and 4) positioned in the readily accessible space above the
upper carriage. This belt treatment unit extends across the width
of the upper casting belt 12 as seen in FIG. 4 and is used to
perform such belt treatments as leveling or coating. In its
operating position as seen in FIG. 4 a pivoted latch 136 has a hook
137 engaged in a recess on the frame of the upper carriage. A
spring 138 urges the latch into its engaged position about the
latch pivot 139. In order to disengage the latch and raise the
treatment unit 85, there is a tension member 140, for example, such
as a rod or cable, pivotally connected at 141 to the upper end of
the latch and at 142 to the front portion of the lift arm above the
level of the pivot 61. Thus, when the lift arm is swung up about
the fulcrum pivot 42, the initial part of this upward motion pulls
on the tension member 140 to unhook the latch 136. The continued
upward swinging movement of the lift arm 40 pulls farther on the
tension member 140 to swing the treatment unit 85 up away from the
upper carriage, as shown at 140' in FIG. 5. This upward swinging of
the treatment unit away from the upper carriage facilitates removal
of the belt 12.
In installations in which a predetermined fixed downward
inclination of the casting region C is desired, the main chassis
frame 24 can be rigidly attached to the U-shaped base unit B. A
three point support for the machine as a whole is then provided by
using three foot pads. Two of these foot pads are then located
beneath the outboard ends of the respective base beams 34 and 36,
i.e. beneath the two arms of the U-shaped base. The third foot pad
is then located beneath the center of the back of the base frame
26.
* * * * *