3.Service conditions
3.1 Indoor use.
3.2 The ambient temperature of the pit type furnace is within the range of –5℃-40℃.
3.3 The monthly average relative humidity in the use area is not more than 85%, and the monthly average temperature is not higher than 30 ℃.
3.4 There is no conductive dust, explosive gas and corrosive gas that can seriously damage metal and insulation around.
3.5 No obvious vibration and turbulence.
4.Structure introduction
This pit type heat treatment furnace is a periodic operation furnace, which is composed of furnace body, sealing system and temperature control system.
The pit type heat treatment furnace is composed of furnace shell, furnace lining, heating elements, muffle tank, furnace cover, fan, furnace cover lifting mechanism, etc.
Furnace shell: welded from section steel and steel plate. A 14# channel steel is welded outside the furnace shell for installing the lifting device of the furnace cover.
Furnace lining: it is a composite structure. The refractory layer adopts light refractory bricks with a specific gravity of 0.6g/cm3, and the insulation layer adopts aluminum silicate refractory fiber. The thickness of furnace lining is 300 mm, which can effectively save energy and reduce consumption.
Heating element: 0cr25al5 high resistance alloy wire produced by Beijing Shougang is wound into a spiral shape and placed on the wire laying brick of the furnace lining. The heating is divided into two temperature control zones.
Muffle tank: 1Cr18Ni9 heat-resistant steel is used for welding and molding, and asbestos packing or "O" type silicone rubber is used for sealing the muffle tank and the furnace cover. And take water cooling below to ensure the long-term use of the sealing ring.
Furnace cover: its panel is processed from 35mm A3 steel plate. The furnace cover insulation box is welded with stainless steel heat-resistant steel and insulated with aluminum silicate fiber cotton. The cover and muffle tank of pit type furnace for heat treatment of metals are sealed by double sealing and water cooling. The furnace cover is equipped with water-cooled fan, three hole drip injector, U-shaped pressure gauge, exhaust pipe, etc. The ammonia gas is extended to the coil at the lower part of the muffle tank by the three hole drip through the pipeline through the pressure stabilization, drying and solenoid valve.
Fan: it is installed on the furnace cover, and its impeller adopts centrifugal fan blades welded with 1Cr18Ni9Ti heat-resistant steel plate, which are assembled after dynamic and static balance tests. The seal between the fan and the shaft adopts the conjoined structure and adopts water cooling.
Pit type furnace cover lifting mechanism: the lifting of furnace cover is completed by electric lead screw lifting mechanism. When the furnace cover needs to be raised, as long as the motor is started, the furnace cover will rise slowly. If the furnace cover needs to be lowered, turn on the motor lead screw to lower, and the furnace cover will be lowered slowly. At the lifting shaft, there are two limit switches. When the lifting shaft rises, the lower limit switch will automatically cut off the power supply of the electric fan to avoid dangerous operation; When the furnace cover is raised enough, the upper limit will automatically cut off the power supply of the motor to avoid accidents.
The temperature is controlled by PID silicon controlled rectifier, and the temperature is controlled by Shanghai Guolong temperature controller. The large and small power can be adjusted, and the three-phase current imbalance can also be adjusted. Shanghai Dahua instrument records the temperature. There is also a complete set of control cabinet, with audible and visual alarm, automatic current cut-off and other functions.
