Bogie Hearth Heat Treat Furnace 8000×2500×2000mm Electrical Car Bottom Type

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.