1. Application
The RT3-1000-12 electric bogie hearth heat treat furnace is mainly used for annealing and solution heat treatment of steel structure parts, alloy parts and stainless steel parts, etc.
3.Structural Introduction
The RT3-1000-12 bogie hearth furnace is mainly comprised of furnace
shell, lining, furnace door and door compression system, bogie, heating
element and fixed device, and temperature control system.
3.1 furnace shell
The car bottom furnace body steel structure is made from
10-14# sectional steel and ≥3mm steel plates. The side pillar and back
pillars are made from sectional steel, and are reinforced with sectional
steel bracings. The external wall of the furnace is painted with 2 layers of
primers, and 2 layers of coating paint. The key part of the furnace is painted
with heat resistant paint.
3.2 lining
The industrial heat treatment furnace body is built with an all-fiber system.
The lining material used is quality aluminum fibers fixed by round steel parts.
The aluminum fibers are pre-compressed into blocks (compression gravity:
≥230Kg/m3 ) and then fixed to the furnace body by round stainless steel parts.
This refractory lining structure has the advantages of low heat conductivity,
strong anti-shock capacity, and anti-erosion. The lining has a total thickness
of 350mm. The silicate aluminum fiber resists a maximum temperature of 1300℃.
The fiber fasteners are made of stainless steel.
3.3 furnace door and door up-down system
The car bottom furnace door is comprised of all-fiber lining and steel
structure casing. The furnace shell is made of 14# plate and 14mm steel plate for
the door frame. The door is built with silicate aluminum fiber blocks same as that
for the furnace body. The overall structure of the furnace maintains its shape while
heated.
Driving method of door: The furnace door is electrically lifted upward and
downward by the hoist. And it is sealed by self-weight of the furnace door.
3.4 bogie
The bogie is comprised of bogie frame, wheels, refractory bricklaying body, heat
resistant bogie hearth plate, heating elements, and bogie driving mechanism.
bogie structure: the bogie frame is made from 18# beam and 14mm steel plates.
The bogie could work for a long time without deformation at full load.
wheel: The wheels are made from ZG55# steel casting. The transmission shaft is
made from 45# steel, and it is heat treated. The transmission bearing is of the heavy
type pillar bearing to bear the weight. There are a total of 6 pairs of wheels, and each
wheel is of diameter 300mm. The bogie is motorized. And the driving motor is equipped
with a braking speed reduction device to relieve the inertia at the start-up and stop
movement. There are 2 limit switches to avoid over-travel of the bogie.
bricklaying body: The bogie is built with a heavy combination of high alumina
refractory bricks, light refractory bricks, and heat preservation bricks. The impacted
parts and weight bearing area are bricked especially with heavy type high aluminum
refractory bricks. There is also free space left for the refractory lining expansion when heated.
bogie hearth plate: 30mm thick Cr25Ni20 heat resistant steel casting part with max
working temperature≤1250℃. It can prevent scales from falling into the heating elements
slot which would form a short circuit.
bogie moving mechanism: The bogie has a self-moving method. The reducing gear drives
the bogie wheel to move. The bogie movement is smooth and stable.
Sealing among furnace door, furnace body and bogie: Sealing between the furnace door
and the furnace body is through spring. The sealing between the bogie and the furnace
body is through soft special shape bricks and fiber cotton block.
3.5 heating element
heating element: The 0Cr27AL7Mo2 (HRE)resistance spiral-shape alloy resistance strips
are mounted in 2 side walls, back wall, furnace door and bogie bottom. The resistance
strips are produced through special molds, and are installed in the furnace wall by porcelain
nails. And there is a porcelain gasket between the fiber wall and the resistance strips to
avoid short-circuit. There are 6 heating zones. All lead-out conductor bars are made of φ16 0
Cr27AL7Mo2 material.
3.6 electrical control system
Temperature control: the furnace adopts intelligent temperature controller to control the
temperature which has self-tuning function to calculate the ideal PID parameter and
achieve a temperature stability. The temperature controller has the functions of
over-temperature alarm and thermal couple breakage protection.
The furnace has 6 temperature control zones for controlling the linkage between the
temperature and the motor movements. Each zone is set with an over-temperature alarm.
The heating loop adopts the double-direction SCR and trigger control. The power is
regulated in the time proportional regulation manner.
The control actuation system is a large-power triggering one complete with a radiator and
an air cooling system. There is also an air switch. The heating loop is equipped with ammeter,
voltmeter, heating element on-off indicator, power-on interlock protection, and safe earthing measures.
Movement control: The control system mainly controls the door up-down movement, door
compression, and door in-out movement. Also the movements are necessarily linked to
ensure the operation safety.
