quench oil Schematic

A tank is a container for quenching media (including water, brine, oil, organic solution, etc.). Usually can also be quenching oil tank , quenching water tank, quenching brine tank, quenching liquid tank, etc. According to the material, shape, size, batch and operation characteristics of the workpiece to be processed, the shape, size, structure, function, mechanization degree and operation method of the quenching tank are very different.

The quenching tank is mainly composed of a tank body, an agitating device, and a temperature control device (including heating and cooling devices).Large quenching tank is also equipped with exhaust, fire extinguishing and other devices.

1) Trough. The tank body is usually welded with 3~5mm (small groove) or 8~12mm (large groove) steel plate, and the surrounding is attached with section steel as reinforcing ribs to improve its strength and rigidity; the base is made of section steel for easy installation and transportation. Its shape is rectangular, square or circular. Generally, the quenching tanks used in box furnaces and salt bath furnaces are mostly rectangular, while the quenching tanks used in well furnaces are mostly circular. Small quenching tank is mostly made of water, oil double or mobile.

In order to ensure that the quenching medium does not overflow outside the groove when the workpiece is quenched into the groove or when the quenching medium expands, and to facilitate medium circulation cooling, an overflow groove is generally provided on the outer edge. The effect of the overflow groove on both sides or around is better than that on one side, so that the supplement of the new quenching medium and the overflow of the hot quenching medium can be properly matched, and the local temperature unevenness can be prevented. The medium inlet of the quenching tank is generally located in the lower part of the tank wall, at an appropriate distance from the bottom of the tank. There is a drain hole at the bottom.

2) Agitator. For the uniformity of the temperature of the quenching medium, to ensure the uniformity of quenching cooling, to reduce the deformation of the workpiece and prevent cracking, the quenching medium should be circulated. The methods of circulating the quenching medium are propeller agitation and jet agitation.

Propeller agitation uses a propeller to agitate the quenching medium, which can obtain good flocculation effect and large displacement, 10 times that of a centrifugal pump with the same power. Agitator speed can not be too high, generally between 100 ~ 450r/min, more than 450r/min, it may be mixed with air. Propeller agitation without pipes, easy installation and convenient maintenance. The disadvantage of such agitators is that they take up more of the available volume of the quenching tank.

The agitating device can be one or several, depending on the size of the quench tank.

3) Heating device. Every 1 kinds of quenching medium has a certain temperature range, beyond the use of the range, the cooling capacity will change. In order to maintain a certain temperature of the quenching medium, the temperature of the quenching medium must be controlled. If the quenching tank is cooled by quenching medium such as hot oil or other organic aqueous solution, the temperature is low at the beginning, and the temperature needs to be increased, so it is necessary to set up a heating device to heat it. The commonly used heating methods are as follows:

① Place a tubular electric heater or a gas radiant tube in a quenching tank to heat the quenching medium.

② Heat the quenching medium outside the quenching tank with fuel or a resistance spiral, similar to an externally heated resistance bath furnace.

③ Heat the quenching medium with steam pipe or hot water pipe.

④ Heat the heated metal block directly in the quenching medium.

4) Cooling unit. All quenching tank, must be hot workpiece quenching, cold workpiece out, quenching medium temperature will increase with the increase of production, especially in the case of continuous production, this phenomenon is more prominent. When the temperature of the quenching medium exceeds its normal use range, the quenching quality of the workpiece cannot be guaranteed, and the production cannot be carried out. Therefore, the hot quenching medium must be cooled to maintain the normal temperature when the workpiece is quenched. The cooling method of quenching medium can be divided into two categories: one is the cooling method of not replacing the quenching medium, and the other is the cooling method of replacing the quenching medium.

The cooling methods without changing the quenching medium include natural cooling, stirring cooling, water jacket cooling, serpentine cooling, spiral cooling, etc,.

Natural cooling. The quenching medium is cooled by the liquid surface and the four walls, and the cooling speed is very slow. When the quenching tank is placed on the ground, it is 3~5 ℃/h, and it is only 1~2 ℃/h when placed in the pit. It cannot be used continuously and is only used for small batch intermittent production.

Agitation cooling. A stirring device is added in the quenching tank to strengthen the circulation of the quenching medium and speed up the heat dissipation. This method is better than natural cooling effect, medium temperature is more uniform, suitable for small batch production.

Jacket cooling. The cooling water flow can be adjusted to control the medium temperature, the structure is simple, the cooling is fast, and the medium temperature is uneven. It is suitable for cycle operation, small batch production and production mode with large batch but long quenching interval, and is suitable for small quenching tank.

coil cooling, which is helical cooling. Both methods can control the medium temperature by adjusting the cooling water flow, and the cooling speed is large, but the medium temperature is uneven. It is suitable for cycle operation, small batch production or production mode with large batch but long quenching interval. It is suitable for medium and small quenching tank.

the cooling method of propeller stirring combined with adjustable water-saving cooler and equipped with guiding channel mode has fast cooling speed, uniform medium temperature, but complicated structure. Suitable for larger batch cycle operation or medium quenching tank.

Change the cooling method of the quenching medium.The cold medium continuously flows and the hot medium continuously flows out, which can quickly reduce the temperature of the hot quenching medium, control the temperature of the quenching medium, the cooling speed is large, and the temperature of the medium is uniform. It is suitable for large and medium-sized heat treatment workshop cycle operation or continuous operation of quenching tank cooling.

5) Vent. The quenching tank with oil or other aqueous solution as quenching medium will inevitably produce a large amount of oil smoke or solution steam due to the hot workpiece quenching into the cooling medium during production. This will cause environmental pollution, make working conditions worse, and bad for the health of workers. For this reason, an exhaust device should be installed on this type of quenching tank to exhaust harmful gases outside the workshop.

6) Fire extinguishing device. When the temperature of the quenching oil exceeds its flash point, it will ignite. Therefore, large quenching oil tanks are equipped with fire extinguishing devices. The fire extinguishing device used is generally a nitrogen automatic fire extinguishing device.