Pit Furnace

Pit furnace is a periodic operation furnace, which is suitable for hardening, annealing, normalizing, carburizing, nitriding, tempering, aging and stress relieving to process the metals parts such as steel parts, long rods, pipes, rollers, bearing, gears, wires and aluminum alloy parts or other metal parts. In most cases, pit furnaces are used for crankshafts in the automotive industry, gears in the aircraft industry, shafts and chains in the machine building industry, drill pipes in the mining industry and in the wind and marine industries. The furnace body is a cylindrical deep pit, constructed in a pit and extending to the ground or slightly above the ground, and the workpieces are placed in a spreader or basket and vertically loaded into the furnace by a crane for heat treatment.

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Precise Temperature Design

The working temperature range of the pit furnace can reach 450-1100°C depending on different designs for various vacuum heat treatments. Pit furnace mainly consists of furnace body, furnace cover, heating element and temperature control system.
Low temperature series (0~750℃) are suitable for tempering, annealing and core drying of steel parts.
Medium temperature series (0~950℃) are suitable for normalizing, annealing and quenching of general metal parts, the heat treatment process is carried out in the air.
High temperature series (0~1300℃) are suitable for normalizing, annealing, quenching of alloy steel parts, high temperature annealing and solution treatment heating of stainless steel parts.

Insert Protective Atmosphere

Pit furnaces are available with gas or liquid fuel, or with electric heating, and in both cases are easy to operate and control. Vacuum atmosphere furnaces are commonly used with various atmospheres such as vacuum, hydrogen, oxygen, nitrogen and inert gases (such as argon). The selection of suitable atmosphere sintering for different materials helps the sintering process, improves the surface accuracy of the finished product, and effectively ensures the toughness and stiffness of the workpiece.

Design Features Of Pit Furnace

Vacuum atmosphere pit furnace is composed of furnace shell, furnace lining, heating element, furnace tank, furnace cover, furnace cover automatic lifting mechanism, vacuum system, cooling water pipeline, temperature and atmosphere control system, etc. Adopt air cooling or wet cooling system and PLC intelligent program temperature control system, with advanced and reasonable structure design, high degree of automation, energy saving and environmental protection.

High Reliability Furnace Shell
The atmosphere pit furnace is a high-temperature full fiber resistance furnace. The shell is made of thickened steel plate rolled and equipped with reinforced steel, the furnace chamber is built with high alumina refractory insulation bricks. The furnace lining is covered with acid aluminum fiber cotton, which is energy-saving and environmentally friendly. The robust reinforced shell and high quality insulation are designed to provide long service life, easy maintenance and optimum thermal efficiency. The picture shows the lining material of the shaft furnace.

Safety Furnace Cover System
The furnace cover is made of thickened steel plate to prevent heat leakage due to thermal deformation, high sealing for saving energy. The furnace cover can be designed for crane lifting or automatic hydraulic opening and closing mechanism. The furnace cover has a safety protection function, when the furnace cover is opened, the control power supply is automatically cut off, and the heating can only be started when the furnace cover is tightly closed to ensure the safety of the operator. The top of the furnace can be equipped with hot air circulation system for stirring the air in the furnace chamber during the sintering process to ensure the uniform temperature inside the furnace.

Flexible Configurations For Various Thermal Processing
The furnace can be equipped with a high-temperature stainless steel vacuum tank. The pre-evacuation method is adopted, and the air inlet and exhaust ports of the protective atmosphere can be used to achieve various heat treatment purposes such as bright annealing, vacuum tempering, and vacuum non-oxidative heating. Atmosphere: air, nitrogen, nitrogen, methanol, argon, ammonia, dissociated ammonia and other inert or reactive process atmospheres are available.

Accurate Temperature Control System
Using intelligent temperature controller and thermocouple temperature control, high temperature control accuracy (±1 degree), sensitive response, programmable PID control, with deviation, over-temperature alarm, safe operation reliable. PID self-tuning, automatic heating, automatic heating, automatic cooling. Over-temperature controller for monitoring the upper temperature of the furnace, over-temperature will automatically cut off the power.

Applied Automatic Control Technology

Electric heating multi-zone synchronous control technology, one-key operation for re-lifting the furnace, the whole process is recorded, and it is completed automatically and efficiently;
Load constant current, constant voltage and constant power control technology, according to different load characteristics, effectively protect the load from damage caused by power failure;
Multiple time curves can be set, and the total number of curve segments is up to 50;
There are two program setting modes of "set value + time value" and "heating section + constant temperature section";
All parameters can be set by key, and the data is automatically saved without loss.

Easy For Installation

The vertical pit furnace design saves valuable floor space compared to horizontally loaded furnace, which require space to swing the door and load/unload. It also provides easy loading as the door raises and swings completely away from the load area to avoid damage. Doors are available in either manual or pneumatic designs. All equipment is factory assembled, tested, tuned and certified prior to shipment.

Technical Specification:

Electric Pit Furnace

Output power	15kW-200kW
Voltage	3 phase 380V 50/60Hz
Furnace chamber	Customized according to the specific workpiece size
Temperature range	650℃-1200℃ Up to 600°C (for low temperature) & Up to 1100°C (for high temperature)
Temperature control mode	PID Automatic Temperature Contro
Temperature uniformity	±5-10℃
Hetaing up time	≤2.5h
Insulation	Vacuum Formed Ceramic Fibre Modules/Ceramic Fibre Blanket & Module/Refractory Brick Lining
Heating media options	Electric/Gas Fired/Oil Fired
Heating elements	Nichrome Wire/Special Alloy Resistance Heating Wire
Instrumentation options	Process Automation Equipment, Thyristor, Programmable Temperature Controller, Temperature Recorder, PLC, SCADA, HMI
Workpiese type	Steel parts, long rods, pipes, rollers, bearing, gears, wires and aluminum alloy parts or other metal parts.
Standard applications	Tempering Carburizing Hardening Normalizing Carbonitriding Case Hardening Gas Nitriding Stress Relieving Wire annealing Decarb annealing Isothermal Annealing Ferritic Nitro Carburizing Annealing/Annealing under protective atmosphere

ROCHO technical team can customize the induction heating power supply for special purposes according to customer requirements, and design capacitors, frequencies and induction coils according to the metal workpiece to be heated and heating requirements to achieve the best heating effect.
When you need to consult or order machine, please provide the following information:
(1) the local industrial voltage;
(2) the name and material of the product to be processed;
(3) the required process: heating, brazing, hardening, melting or annealing;
(4) the size of the product to be processed, such as diameter and length and if drawings can be provided.

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