Reheat furnace apparatus and method of use

A reheat furnace for reheating elongated metal workpieces includes an entrance end portion and an exit end portion opposite to the entrance end portion, and two side walls spaced apart from each other and extending between the entrance and exit end portions. A conveyor mechanism is provided to convey the workpieces from the entrance end portion to the exit end portion. The reheat furnace is constructed to have a buffer zone adapted to temporarily contain workpieces without applying direct heat to the workpieces and a heating zone adapted to apply direct heat to the workpieces.

FIELD OF THE INVENTION 
This invention concerns the field of reheat furnaces and more particularly 
to a reheat furnace apparatus and method for reheating steel blooms. 
BACKGROUND OF THE INVENTION 
In the process of hot rolling elongated steel billets and blooms having a 
substantially rectangular cross-section, blooms are usually reheated in a 
reheat furnace after being produced by a casting machine. The workpieces 
are reheated in the reheat furnace up to a temperature suitable for 
subsequent rolling that reduces them further. Examples of reheat furnaces 
are provided in the publication, The Making, Shaping, and Treating of 
Steel, Ninth Edition, Herbick and Held, pp. 667-674, (1971). 
Reheat furnaces are either batch-type or continuous. In batch-type reheat 
furnaces the material remains on the hearth in a fixed position until it 
is heated to the rolling temperature. In continuous furnaces the 
workpieces are heated to the rolling temperature as they are moved through 
the furnace. Continuous furnaces include pusher-type, walking-beam type 
and rotary-hearth type furnaces. 
Walking-beam type continuous reheat furnaces include an entrance end, an 
exit end opposite to the entrance end, and two side walls spaced apart 
from each other and extending between the entrance and exit ends. A feed 
conveyor having driven rollers is provided near the entrance end of the 
furnace and extends between the side walls. A charging mechanism near the 
entrance end of the furnace has charging carriers that travel into and out 
of the furnace to transfer workpieces from the feed conveyor to a 
walking-beam conveyor mechanism inside the furnace. 
The charging mechanism has arms or carriers that engage the underside of a 
workpiece positioned on the feed conveyor. The entrance end of the furnace 
is opened and the carriers move the workpiece perpendicular from the feed 
conveyor through the open entrance end of the furnace onto the 
walking-beam mechanism in the furnace. The walking-beam mechanism 
transports the workpieces from the entrance end portion to the exit end 
portion through a heating area. The walking beam mechanism walks the 
blooms across the furnace and places them on a discharge conveyor located 
near the exit end of the furnace, which removes the blooms from the 
furnace. 
One process includes a ladle metallurgical facility, a vacuum tank 
degasser, a continuous caster, a reheat furnace and a rolling mill. The 
reheat furnace is disposed along the process line downstream from the 
continuous caster and upstream from the rolling mill. The caster operation 
and the rolling mill operation are designed to operate at specific 
production rates. However, due to production problems at the rolling mill, 
the production rates of the caster and the rolling mill are not always 
concurrent. 
In the event of emergencies in production, the production rate of the 
reheat furnace may have to be decreased to accommodate variations in 
production at the rolling mill. For example, if there is a rolling mill 
outage due to an equipment failure, loss of power at the rolling mill 
necessitating its shut-down, or when the roll spacings are adjusted at the 
rolling mill, production at the reheat furnace must be decreased or 
stopped. After the reheat furnace capacity is met, there is no available 
space in the reheat furnace to store the blooms and backlogs of blooms 
occur upstream of the reheat furnace. These bloom backlogs are undesirable 
because the blooms cool to ambient temperature if allowed to remain 
outside the reheat furnace for too long. This is inefficient in that it 
requires additional time and energy to heat these blooms again. Also, for 
some grades of steel this heat loss will result in poor metallurgical 
quality of the blooms and may even require them to be scrapped. A typical 
charging machine for a reheat furnace transfers the workpieces from the 
feed conveyor to the first position in the heating zone of the furnace, 
the heating zone having burners for applying direct heat to the 
workpieces. 
SUMMARY OF THE INVENTION 
The present invention relates to a reheat furnace for reheating blooms or 
other elongated workpieces, which overcomes the aforementioned problems of 
the prior art and provides additional advantages. The present reheat 
furnace overcomes the backlog problems of conventional reheat furnaces by 
having a built-in buffer zone that temporarily stores the workpieces in 
the event of shut-down of the rolling mill, during emergencies, or for 
metallurgical purposes. The workpieces will either be transferred beyond 
the buffer zone into the heating zone during normal operation or, in the 
event of a rolling mill outage, deposited into one of 8 locations in the 
buffer zone. Also, the arrangement of the reheat furnace and the charging 
mechanism results in low furnace heat loss. 
In a preferred form, the reheat furnace for reheating elongated steel 
workpieces includes an entrance end portion and an exit end portion 
opposite to the entrance end portion, and two side walls between the 
entrance and exit end portions. The furnace also includes a roof and a 
bottom portion. A conveyor mechanism conveys the workpieces in a direction 
transverse to their length from the entrance end portion to the exit end 
portion. The furnace is constructed with a buffer zone having no heating 
devices, e.g., burners, located therein for applying direct heat to the 
workpieces. The furnace is also constructed with a heating zone having 
heating devices located therein that apply direct heat to the workpieces. 
An in-furnace feed conveyor is provided to feed workpieces in a direction 
of their length into the furnace entrance end portion through an opening 
in the sidewall. A walking beam conveyor conveys the workpieces in a 
direction transverse to their length from the entrance end portion to the 
exit end portion. A charging mechanism at the entrance end portion of the 
furnace has carriers that transfer workpieces from the in-feed conveyor 
within the furnace to selected locations on the walking beam conveyor 
mechanism in the buffer zone and the heating zone. An in-furnace discharge 
conveyor is provided to discharge workpieces in a direction of their 
length from the furnace exit end portion through an opening in the 
sidewall. 
The present reheat furnace does not suffer from conventional backlog 
problems. The reheat furnace of the invention is designed to have a longer 
length than conventional furnaces to provide a built-in buffer zone. The 
reheat furnace is designed with a buffer zone despite the inherent 
increased costs associated with constructing such a larger furnace. The 
present reheat furnace employs the buffer zone even though it may decrease 
production rates when used. The reheat furnace is designed with the buffer 
zone despite such considerations, because of the significant advantages 
the buffer zone presents in preventing production backlogs. 
The furnace charging machine transfers a workpiece to any of several 
available locations in the buffer zone. These buffer zone locations 
comprise the first region of the furnace, downstream from the furnace 
entrance end portion. From each of these locations the workpieces will 
have different lengths and times of travel before reaching the furnace 
heating zone. The charging machine can bypass the buffer zone entirely 
during normal operation when there is no rolling mill outage. In addition, 
operation of the reheat furnace may be adjusted to accommodate a rolling 
mill problem anticipated to last for a particular length of time. Thus, 
not only can the reheat furnace of the invention accommodate backlogs once 
they occur, its process control system reacts to backlogs of a particular 
anticipated duration. 
In its broader aspects, the invention is a mechanism for lifting and moving 
blooms within a furnace including a plurality of elongated carriers 
movable along a path at least a portion of which is within the furnace. 
The carriers are adapted to travel along the path between a location where 
they receive a bloom and a location in the heating zone where they deposit 
the bloom normally. The carriers are adapted to travel along the path to 
selected locations in the buffer zone. Actuators each vertically move the 
workpiece engaging end of an associated charging carrier. Stationary 
driving mechanisms are each adapted to drive an associated one of the 
carriers into and out of the interior of the furnace. 
At least one of the feed mechanism and the discharge mechanism each 
comprises a conveyor having driven rollers within the reheat furnace for 
feeding workpieces in a direction of their length from one side wall 
toward the other. A wall at the entrance end portion extends between the 
side walls. The entrance wall has openings each corresponding to an 
associated charging carrier and having a size approximating a 
cross-sectional area of the associated charging carrier. 
By feeding workpieces on the feed conveyor inside the furnace, the present 
reheat furnace utilizes an entrance end wall design that minimizes heat 
loss. The furnace charging machine of the invention does not move a 
workpiece from a location on a feed roll conveyor outside the furnace to 
the feed conveyor inside the furnace. Instead, the present furnace charger 
carriers normally extend through openings in the entrance end wall that 
approximate the cross-sectional area of the carriers, to transfer a 
workpiece from the in-furnace feed roll to the walking beam mechanism in 
the furnace. 
In its broader aspects, the method of reheating metal workpieces of the 
present invention includes the step of feeding workpieces into a reheat 
furnace. The method includes conducting a step selected from the group 
consisting of transferring the workpieces beyond the buffer zone to the 
heating zone, and transferring the workpieces through the buffer zone and 
to the heating zone. The workpieces are transferred through the heating 
zone and removed from the furnace. 
More particularly, the present method includes the steps of feeding the 
workpieces into the reheat furnace along the feed conveyor rollers in a 
direction of their length. The underside of the workpieces are each 
engaged with leading end portions of the charging carriers. The leading 
ends of the charging carriers are raised and lift each of the workpieces 
from the in-furnace feed conveyor rollers. The workpieces are transferred 
transverse to their length from the feed rollers to the walking beam 
mechanism in the buffer zone, in the event of a mill outage downstream of 
the reheat furnace. No heating devices are located in the buffer zone to 
apply direct heat to the workpieces in the buffer zone. The workpieces are 
transferred transverse to their length by the walking beam mechanism from 
the buffer zone into the heating zone. Direct heat can be applied to the 
workpieces from heating devices located in the heating zone. The 
workpieces are removed from the reheat furnace along the discharge rollers 
in a direction of their length. 
Another embodiment of the invention is directed to a method of reheating 
metal workpieces in a reheat furnace located in a path for conveying 
workpieces between a continuous caster and a rolling mill, during 
operation of the caster and an outage of the rolling mill halting its 
operation, comprising the steps of: 
(a) receiving a signal indicating outage of the rolling mill, 
(b) receiving workpieces from the caster into the reheat furnace, 
(c) transporting each of the workpieces to a buffer zone in the reheat 
furnace in response to the signal, the buffer zone having no heating 
devices for applying direct heat to the workpieces, 
(d) transporting the workpieces to a heating zone having heating devices 
that apply direct heat to the workpieces, and 
(e) repeating the steps (b) and (c) until the caster operation halts, the 
rolling mill operation restarts, or the buffer zone is filled with 
workpieces. 
The workpieces may be advanced in the buffer zone during the rolling mill 
outage. Motion of the workpieces in the reheat furnace may be halted in 
response to the signal anticipating the duration of the rolling mill 
outage. Also, the heating temperature in the heating zone may be adjusted 
in response to the signal anticipating the duration of the rolling mill 
outage.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Turning now to the drawings, and to FIGS. 1 and 2 in particular, the reheat 
furnace apparatus of the invention is shown generally at 10. The reheat 
furnace apparatus 10 is used to reheat elongated steel workpieces or 
blooms B having a substantially rectangular cross-section. An in-furnace 
feed conveyor 12 feeds the workpieces B into a reheat furnace 14 along a 
path D. A walking beam mechanism 16 conveys the workpieces B transverse to 
their length along the path E. The furnace 14 is constructed to have a 
buffer zone 18 having no heating devices therein, such as burners or the 
like, which would apply direct heat to the workpieces B. The furnace 14 is 
also constructed to have a heating zone 20 with heating devices such as 
burners that apply direct heat to the workpieces B. A charging mechanism 
22 is provided having charging carriers 24 that transfer workpieces B 
transverse to their length to selected locations on the walking beam 
mechanism 16 in the buffer zone 18 or the heating zone 20. A discharge 
conveyor 26 discharges workpieces B out of the furnace along a path 
extending in a direction F. 
The furnace 14 is a side charge and discharge furnace, constructed with an 
entrance end portion 28 and an exit end portion 30 opposite to the 
entrance end portion 28. Two side walls 32, 34 are spaced apart from each 
other and extend between the entrance and exit end portions 28, 30. The 
furnace has an entrance end wall or charge wall 35 and an exit end wall 
37. The furnace 14 is preferably constructed to have the heating zone 20 
located downstream from the buffer zone 18. The heating zone 20 is a 
multiple heating zone including a heating region 36 and a soak region 38. 
Ultra-low NOx burners 48 are arranged in a top and bottom fired 
configuration known in the art. 
It should be appreciated that modifications to the reheat furnace by those 
skilled in the art are contemplated by the invention. For example, the 
reheat furnace could be an end charge and discharge furnace, the buffer 
and heating zones could be different sizes, and the buffer zone could be 
located downstream from the heating zone. 
The reheat furnace 14 includes other furnace components as is known to 
those skilled in the art, including a recuperator 40 for preheating 
combustion air, a positive draft ejector type stack 42, a flue 44, a 
damper 46, and all combustion control systems and necessary auxiliary 
systems. Combustion product gases exit the furnace 14 through the flue 44 
above the feed conveyor 12. The gases then pass through a duct to the 
recuperator 40, damper 46 and ejector drive stack 42. The recuperator 40 
preheats the combustion air to approximately 900 degrees F. 
The combustion system is constructed in a manner known to those skilled in 
the art, and includes heaters or burners 48 disposed at locations in the 
furnace for applying direct heat in the heating region 36 and the soak 
region 38 of the heating zone 20. No burners are provided in the buffer 
zone 18 and no direct heat is applied to the blooms B in the buffer zone 
18. In the heating region 36 direct heat is applied from the burners 48 to 
the blooms B located therein to raise the temperature of the blooms B to 
near the discharge temperature. In the soak region 38 direct heat is 
applied from the burners 48 to blooms B located therein to equalize the 
blooms B at their discharge temperature prior to exiting the furnace 14. 
Combustion control systems are used for providing the desired heat in the 
heating and soak regions 36, 38. 
The primary variable in the combustion control systems used for the heating 
zone 20 is the temperature in the furnace 14. A secondary variable in the 
combustion control systems is the fuel-to-air ratio. These variables also 
determine furnace temperature regulation when the buffer zone 18 is 
utilized. 
The buffer zone 18 may have any length, although a length sufficient to 
accommodate the width of eight blooms B is preferred. The first, fifth, 
seventh and ninth positions in the furnace beyond the feed conveyor 
("B.sub.1, B.sub.5, B.sub.7 and B.sub.9 ") are shown in FIG. 2. The buffer 
zone includes positions B.sub.1 -B.sub.8, the first position in the 
heating zone being B.sub.9. In the buffer zone 18, although no direct heat 
is applied to the blooms B, the blooms B will not cool to ambient 
temperature. The blooms B are heated indirectly by excess radiation, 
convection, and conduction heat from the heating zone 20. 
Blooms B are preferably hot charged into the furnace 14 from the caster. 
The charge and discharge temperatures will vary according to the grade of 
material and the production rate. The bloom tip-to-tail charge temperature 
may vary about 110 degrees F. The following Table 1 shows theoretical 
furnace performance during normal operation, the indicated production 
rates being when the buffer zone 18 is bypassed. The following fuel rates 
are short ton rates at test conditions with the furnace in a new condition 
and at thermal equilibrium. 
TABLE 1 
__________________________________________________________________________ 
Case 1 
Case 2 
Case 3 
Case 4 
Case 5 
__________________________________________________________________________ 
AISI Grade 8,620 
4,140 
1,070 
52,100 
12xxx 
Charge Temperature (.degree.F.)(Avg.) 
1,290 
1,290 
1,380 
1,380 1,380 
Discharge Temperature (.degree.F.)(Avg.) 
1,995 
1,995 
1,890 
1,920 2,190 
Maximum Temperature Differential 
.+-.25 
.+-.25 
.+-.25 
.+-.25 
.+-.25 
(.degree.F.)(Hot-Cold) 
Production Rate (tons/hour) 
180 180 180 180 180 
Fuel Rate (Million Btu/ton) 
0.55 0.55 0.47 0.5 0.62 
Scale Loss (%) 0.65 0.65 0.65 0.65 0.65 
*NO.sub.x Emissions (pounds/Million Btu) 
0.09 0.09 0.09 0.09 0.09 
__________________________________________________________________________ 
The fuel that is used is natural gas with a minimum net heating value of 
1000 Btu/SCF supplied to the furnace at a minimum pressure of 40 psi. 
Firing is performed with 900.degree. F. combustion air. The blooms B are 
preferably 10 inches by 13 inches by 40 feet, although the bloom 
dimensions may vary. The blooms B range from 19 feet to 46 feet in length. 
When the buffer zone 18 is used, the walking beam conveyor 16 transfers the 
workpieces B from the furnace entrance end portion 28 to its exit end 
portion 30, during which the workpieces B pass through the buffer zone 18, 
the heating region 36 and the soak region 38. As shown in FIG. 2, the 
walking beam conveyor 16 includes inclined ramps 50. An intermediate lift 
frame structure 52 contains wheel assemblies 54 arranged in a two wheel 
system group. Each upper wheel 60 of a group is mounted on a different 
shaft at a different height than each lower wheel 58 of the group. The 
lower wheels 58 ride on the ramps 50, while the upper wheels 60 support a 
main frame structure 62. The intermediate lift frame 52 includes an 
intermediate frame beam 64. The main frame 62 includes a main frame beam 
66. The main frame beam 66 supports movable horizontal skids 68 above the 
beam on posts 70. The intermediate frame beam 64 supports a fixed skid 72 
on posts 74. The blooms B in the furnace 14 are supported on their bottom 
surface by fixed skids 72, except when being moved by the walking beam, 
when they are supported by the movable skids 68. The movable and fixed 
skids 68, 72 are water cooled. 
A hydraulic cylinder 76 is connected to the main frame beam 66 and moves it 
longitudinally upon the upper wheels 60, toward and away from the furnace 
exit end portion 30. A hydraulic cylinder 78 is connected to the 
intermediate frame beam 64 and moves it up and down the ramps 50 upon the 
lift wheels 58. When the intermediate frame beam 64 is moved by the 
cylinder 78, the upper wheels 60 roll underneath the main frame beam 66, 
while the lower wheels 58 roll up or down the associated ramps 50. As a 
result, the main frame beam 66 is moved vertically, i.e., lifted or 
lowered, while remaining at a fixed longitudinal location, unless moved 
independently by the cylinder 76 to advance the workpieces B supported on 
the movable skids 68 toward the furnace exit 30. By moving the main frame 
beam in the opposite direction, the cylinder 76 also moves the movable 
skids 68 back to the home position. During normal operation, the walking 
beam conveyor 16 cycles the blooms B through the furnace heating zone 20 
at a selected travel rate. During a rolling mill outage the walking beam 
conveyor 16 either cycles the blooms B through the buffer zone 18 and the 
heating zone 20 or holds the blooms B in position in the furnace 14. 
The cycle of walking beam movement consists of five strokes. In the first 
stroke, the cylinder 78 moves the intermediate frame beam 64 on the lower 
wheels 58 up the inclined ramps 50 while the main frame beam 66 remains in 
the horizontally fixed home position shown in FIG. 2. This raises the 
movable skids 68 vertically, from a workpiece pass line P to four inches 
above the workpiece pass line P, lifting the blooms from the fixed skids 
72. In the second stroke, the cylinder 76 moves the main frame beam 66 
horizontally approximately eighteen inches on the upper wheels 60 while 
the intermediate frame beam 64 is in the raised position. In the third 
stroke, the cylinder 78 moves the intermediate frame beam 64 downward, 
while the main frame beam 66 remains extended at a horizontally fixed 
position. This vertically lowers the intermediate frame beam 64 and the 
movable skids 68 through the pass line P to a vertical position four 
inches below the pass line P, and the blooms are again supported on the 
fixed skids 72, but at a horizontally advanced location toward the exit 
portion of the furnace. In the fourth stroke the transverse cylinder 76 
moves the main frame beam 66 horizontally eighteen inches back to the home 
position while the intermediate frame beam 64 is in the lower position. 
Finally, in the fifth stroke the cylinder 78 moves the intermediate frame 
beam 64 on the wheels 58 along the ramps 50 to raise the movable skids 68 
four inches to the home position at the pass line P. The total walking 
beam cycle lasts approximately 45 seconds. Normally, blooms B travel 
through the reheat furnace at a rate of 16-20 blooms/hour. 
The furnace entrance end portion 28 includes a charge wall 35 extending 
between the side walls 32, 34. The wall 35 has openings 90 each 
corresponding to an associated charging carrier 24 and having a size 
approximating a cross-sectional area of the associated charging carrier 
24. The carriers 24 are movable within the openings 90 to move workpieces 
B from the in-furnace feed conveyor 12 to the walking beam mechanism 16. 
By designing the charge wall 35 with the openings 90 having a 
cross-sectional opening slightly larger than the cross-sectional area of 
each charging carrier 24, the carriers 24 can move the workpieces B within 
the furnace with minimal heat loss from the furnace. Openings 92 are also 
provided in the charge wall 35, offset from the openings 90, to 
accommodate the feed roll assemblies 80. The openings 92 permit the drives 
for the feed roll assemblies 80 to be located outside the furnace and 
insulated from the furnace by the wall 35. 
The feed conveyor 12 extends into the furnace entrance end portion 28 from 
the side wall 32 to the side wall 34. The feed conveyor 12 includes a 
plurality of the driven roll assemblies 80. Each of the roll assemblies 80 
has the drive mechanism located outside the furnace 14 and driven rollers 
82 located within the furnace 14. The rollers 82 are water cooled. 
Blooms B travel into the furnace 14 on the feed rollers 82 along the path 
D. The discharge conveyor 26 is located at the furnace exit end portion 30 
and extends from the side wall 32 to the side wall 34. The discharge feed 
conveyor 26 includes a plurality of roll assemblies 84 each having a drive 
mechanism located outside the furnace 14 and driven rollers 86 located 
within the furnace 14. The roll assemblies 84 extend through openings 
similar to those in the charge wall 35. The rollers 86 are water cooled. 
Blooms B travel out of the furnace 14 on the discharge rollers 86 along 
the path F. The rollers 82, 86 are made from a high temperature steel 
alloy. Each of the roll assemblies 80, 84 is independently driven by a 7.5 
horsepower motor reducer assembly, designed to move the blooms B at about 
300 feet per minute. 
The furnace charging machine 22 preferably includes four horizontal 
charging carriers 24 each having a first end portion 94 and a second 
workpiece engaging end portion 96. Each of the carriers 24 is made from 
rolled steel plate. Each charging carrier 24 extends between successive 
drive roll assemblies 80. The stationary driving mechanisms 100 are each 
adapted to drive an associated one of the charging carriers 24 between an 
extended position within the furnace 14 and a retracted position away from 
the furnace 14. 
Each of the carriers 24 preferably has a rectangular cross section and a 
lower surface 104, although the carriers 24 are not limited to any 
particular cross-sectional shape. Each driving mechanism 100 includes a 
frame 106 and the driving pinion 108 rotatably connected to the frame 106. 
The pinion 108 has a plurality of teeth 110 along its peripheral surface. 
The rack 112 is disposed along a portion of the length of the carriers 24 
at their lower surface 104. The rack 112 has teeth 114 that correspond to 
and mesh with the pinion teeth 110. 
Activating a motor drives the pinions 108 to drive the carriers 24, either 
toward the furnace 14 or away from the furnace 14. A hold down roller 118 
is mounted to the frame 106 to ensure that the rack 112 and pinion 108 of 
each of the carriers 24 are engaged regardless of the position of the 
carrier 24. 
Hydraulic cylinders 102 vertically move the second end portions 96 of the 
charging carriers 24. This permits the carriers 24 to lift a bloom B from 
the rollers 82 and, after the carriers 24 are extended into the furnace, 
to lower the bloom B onto the walking beam conveyor 16. As shown in FIGS. 
4 and 5, the vertical movement of the carriers 24 caused by the hydraulic 
cylinders 102 is effected by an apparatus that includes the roller 120 
rotatably connected to a frame 122. Each roller 120 has a peripheral 
groove 124 for receiving the rack 112. Each cylinder 102 has a piston 126 
connected to the frame 122. The cylinder 102 has a lower end 128 that is 
pivotably movable. By extending the piston 126, the carrier 24 is raised 
to a predetermined height. The carrier 24 is lowered by retracting the 
piston 126 into the cylinder 102. 
The furnace charger 22 moves its carriers 24 in a five step cycle, during 
which it charges a bloom B either directly into the heating zone 20 during 
normal furnace operation, or into the buffer zone 18 in the event of a 
rolling mill outage. The carriers 24 begin in a rearward home position 
shown in FIG. 4. In the first step, each pinion 108 is rotated in a 
direction toward the furnace 14 and moves the carriers 24 horizontally 
from the home position to a pick up position between successive feed roll 
assemblies 80 in the furnace 14 and below a bloom B to be charged. In the 
second step, the cylinders 102 are actuated and the pistons 126 extended 
to vertically raise the carriers 24. 
In the third step, if a signal is sent to the furnace charger 22 indicating 
a rolling mill outage, the pinions 108 are driven to horizontally move the 
carriers 24 to a deposit position above the next available position 
furthest into the furnace in any one of the eight locations in the buffer 
zone 18. During normal operation, the third step consists of advancing the 
carriers 24 into the furnace 14 directly to a ninth furnace deposit 
position B.sub.9 (i.e., the first position in the heating zone 20), 
located approximately 18 feet from the furnace entrance end 28. 
In the fourth step, the pistons 126 are retracted into their associated 
cylinders 102 to vertically lower the charging carriers 24 below the fixed 
and movable skids 72, 68, to deposit the bloom on the fixed and movable 
skids 72, 68 in one of the eight buffer zone 18 locations or in the ninth 
furnace position B.sub.9. In the fifth step, the pinions 108 are rotated 
in the opposite direction away from the furnace 14 to substantially 
horizontally retract the carriers 24 from the furnace 14 back to the home 
position. The total furnace charging cycle lasts approximately 40 seconds. 
The reheat furnace apparatus includes a processor that electrically 
communicates with a hydraulic valve that either energizes or deenergizes a 
hydraulic motor associated with the pinions of the driving mechanism and 
sensing devices at least at the caster and the rolling mill. The processor 
is programmed to accomplish the following functions. 
During normal operation of the reheat furnace apparatus 10 the caster and 
the rolling mill are operating within normal production parameters. Blooms 
B are fed from the caster into the furnace 14 by the feed conveyor 12 in a 
direction of their length. The furnace charger 22 is activated to raise a 
bloom B from the in-furnace feed conveyor rollers 82 and transfer it 
transversely beyond the buffer zone 18 to the ninth furnace position 
B.sub.9 in the heating region 36 of the heating zone 20 on the fixed and 
movable skids 72, 68. The buffer zone is empty during normal operation. 
The bloom B is advanced through the furnace 14 toward the exit end portion 
30 by cycling of the walking beam conveyor 16. During each cycle, the 
bloom B is lifted above the bloom pass line P and moved horizontally to a 
location approximately eighteen inches advanced from the prior location. 
In this manner the bloom B is transported step-wise through the heating 
and soak regions 36, 38 and onto the discharge conveyor rollers 86, on 
which the bloom B is transported out of the furnace 14 in a direction of 
its length. The bloom B is then transported to the rolling mill. 
The operation of the reheat furnace apparatus 10 during a scheduled or 
unscheduled rolling mill outage while the caster continues to operate 
requires use of the buffer zone 18. The buffer zone 18 is used only when a 
production "buffer" is required between the casting operation and rolling 
mill operation and is required for emergency or metallurgical purposes. 
The reheat furnace 14 continues to receive blooms B from the caster but 
will not discharge any blooms B from the furnace 14 to the rolling mill. 
This condition continues until the mill restarts or the buffer zone 18 is 
filled with blooms B. When the buffer zone is filled with blooms the 
processor may halt the walking beam motion and adjusts the combustion 
system in accordance with the estimated delay time and bloom temperature 
requirements. 
More specifically, during a rolling mill outage while the caster continues 
to operate, blooms B are fed from the caster into the furnace 14 by the 
feed conveyor 12 in a direction of their length. In response to signals 
received from a sensing device at the rolling mill indicating an outage 
there, the processor sends a control signal to the hydraulic valve and the 
hydraulic motor. This control signal activates the motor to rotate the 
drive pinions and advance the carriers a desired distance to deposit 
blooms in the buffer zone of the furnace. The control signal rotates the 
pinions and activates the furnace charger piston to raise a bloom B from 
the feed conveyor rollers 82 and transfer it transversely on the fixed and 
movable skids 72, 68 to the last available buffer zone location farthest 
in the furnace 14. 
The walking beam 16 either cycles the blooms B through the furnace 14 or 
holds them in position during a rolling mill outage. The walking beam 
conveyor rate may be increased to empty the buffer zone when the processor 
detects that the buffer zone is nearly filled, such as when a bloom is 
placed in the fifth position B.sub.5 in the buffer zone. When the buffer 
zone 18 is filled, the caster operation is preferably adjusted to cease 
conveying blooms B to the reheat furnace 14. The walking beam conveyor may 
either have its rate increased if there is room available in the heating 
zone or it may be stopped if no room is available in the heating zone. The 
combustion system either heats the blooms B to the specified temperature 
or holds them at temperature, depending on the particular operating 
conditions. The reheat furnace 14 thus operates to maintain heat in the 
blooms B and control the parameters to insure that the blooms B have good 
metallurgical quality by not allowing blooms to be backlogged between the 
reheat furnace and the rolling mill. The processor is adapted to control 
furnace conditions such as temperature and gas flow of the furnace. Upon 
receiving signals from sensing devices indicating that the rolling mill 
has restarted, the processor may increase the rate at which the walking 
beam conveys the blooms through the furnace to empty the buffer. The 
heating rate of the furnace is also increased simultaneously. 
The furnace 14 is also capable of a cold charge operation when the caster 
is out of service. During the cold charge operation the reheat furnace 
operates at a much slower rate than normal, consistent with metallurgical 
and production requirements. 
While particular embodiments of the present invention have been illustrated 
and described herein, they are not intended to limit the invention to such 
disclosures and changes and modifications may be made thereto within the 
scope of the following claims.