Pit Type Annealing Furnace

Danyang Dingfeng Industrial Furnace Co., Ltd. is one of the most reliable manufacturers and suppliers of pit type annealing furnace in China. If you're going to wholesale durable pit type annealing furnace made in China, welcome to get pricelist from our factory. All customized products are with high quality and low price.

Product Definition

 

Pit type annealing furnace is a vertical furnace that goes in the ground. Used for long or heavy parts – shafts, steel rods, pipes, wire coils, rolls. The whole idea is controlled heating and slow cooling. Gets rid of internal stress, makes the metal softer and more ductile, refines the grain. Improves machinability – you can actually cut it without killing your tools.

Working Principle

 

You load from the top. Crane or hoist picks up the parts, lowers them straight down into the pit.

Close the cover. That seals it up.

Heat comes from electric elements or gas burners. They ramp up slowly – annealing isn't a fast process. You follow a curve.

The control system watches the temperature and the soak time. You don't want to overshoot. Annealing needs precision.

After the soak, you cool slowly. Some people cool inside the furnace with the heat off. Some pull the parts out into a cooling station. Depends on the material and what you're trying to achieve.

When the cycle finishes and the temperature is safe, pull the parts out.

• Good for long and coiled parts. The vertical pit design handles long pipes, shafts, wire coils, cables. No bending because gravity pulls them straight.
• Atmosphere sealing. The lid has a sand seal or a pneumatic compression mechanism. That matters if you're doing bright annealing under protective gas. You can't have air leaking in. A good sand seal holds about 10 to 15 millibars of positive pressure. That's enough to keep oxygen out.
• Even temperature from top to bottom. This is where Pit type annealing furnaces fail if not designed right. Heat rises. The top wants to be hotter than the bottom. We fix that with multi-zone heating – separate zones every meter or so, each with its own thermocouple and control. Plus a recirculation fan at the bottom pushing hot air up.
• Saves floor space. Goes in the ground. Only the lid and maybe a small platform sit above floor level.
• Heavy load capacity. The pit structure is just a concrete hole with a steel liner. It can handle heavy loads. The limit is your crane and your lifting fixture.
• Energy efficient. Depends on the insulation. Fiber modules work well – low heat storage, heat up fast, cool down fast.

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