1. Application
The RT3-70-6 electrical bogie hearth furnace is mainly used for tempering, structural steel, cast steel, spring steel and tool steel.
2. Structural Introduction
The RT3-70-6 bogie hearth furnace is mainly comprised of furnace
body, lining, furnace door and door compression system, bogie, heating
element, circulation device and temperature control system.
2.1 furnace body
The bogie hearth furnace design body steel structure is made from
10-12# 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.
2.2 lining
The wholesale bogie hearth 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
240mm. The silicate aluminum fiber resists a maximum temperature of 950℃.
2.3 furnace door and door up-down system
The wholesale car bottm furnace door is comprised of all-fiber lining and steel
structure casing. The door frame is made of 10mm steel plate. 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 spring.
2.4 bogie
The bogie is comprised of bogie frame, wheels, refractory bricklaying body,
heat resistant bogie face plate, heating elements, and bogie driving mechanism.
bogie structure: the bogie frame is made from 14# beam and 10mm 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 4 pairs of wheels, and each
wheel is of diameter 240mm.
bricklaying body: The bogie is built with a combination of high alumina refractory bricks,
light refractory bricks, and heat preservation bricks. The bricklaying body of the bogie
has heating elements installation slot for easy installation of the heating elements. 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 face plate is cast with CrMnN, 30mm. The max temperature≤950℃. It has
long - term use without deformation and cracking.
Sealing: The seal between furnace door and furnace body and bogie is more important.
The seal between furnace door and furnace body adopts spring compression structure.
The seal between bogie and furnace body is seal of special-shaped brick and fiber
cotton block.
2.5 heating element
heating element: The 0Cr25AL5 resistance spiral-shape alloy resistance strips are
mounted in 5 side walls, two 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 1 heating zone. All
lead-out conductor bars are made of φ16 0Cr25AL5 material.
2.6 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 1 temperature control zone 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.
2.7 Hot air circulating system:
It is mainly comprised of a centrifugal fan and an air guide plate in the furnace. The
heat emitted by the heating element is evenly blown to the effective working area by
the circulating fan through the wind guide plate. The air guide plate is made of 1Cr18Ni9,
and the fan and shaft are made of 1Cr18Ni9Ti. In order to ensure the normal use of
bearings, the cooling method is air cooling.
Guide device: it mainly circulates the air generated by the circulating fan in the furnace
along the direction of the guide plate effectively in the furnace, so as to make the air in
the furnace produce rapid convection, so as to achieve the goal of temperature uniformity.
The materials of wind guide plate and framework are all made of 304 stainless steel plate.
The air guide plate and the framework are connected in a movable way to ensure the free
expansion of the air guide plate under high temperature, and it is convenient for repair and
maintenance.
