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High Pressure Gas Quenching Technology For Gears

Vacuum high pressure gas quenching and its advantages

After the workpiece is heated at the austenitizing temperature, 1~2MPa high-pressure gas quenching can achieve the quenching effect of static oil or high-speed circulating oil or even water. The gas quenching of the workpiece is different from the liquid medium quenching mechanism. The intermediate cooling is uniform, which can achieve uniform cooling from the surface to the inner layer, so the gas quenching distortion is small, and less grinding can be achieved. High-pressure gas quenching adopts neutral gas N2, reducing gas H2 and inert gases Ar, He, etc. These gases are discharged into the atmosphere without pollution, avoiding the flue gas pollution caused by oil quenching, and eliminating the lye cleaning process and Drainage of oily liquids. The surface cleanliness of the treated parts is high, there is no need for subsequent cleaning and shot blasting procedures, and there is no SO2 and CO emission problems, so it belongs to the clean heat treatment technology.

During high-pressure gas quenching, the high-pressure airflow can control the pressure and flow of the gas through the computer, change the cooling characteristics of the gas, and combine with the supercooled austenite transformation phase diagram of the steel to achieve the most ideal quenching and cooling, and obtain the ideal metallographic structure, Effective hardened layer depth and heat treatment distortion.

(1) Vacuum high pressure gas quenching furnace and technology

The rear chamber of the high-pressure gas quenching furnace is a sealed heating chamber structure, and the front chamber is subjected to high-pressure gas quenching. The gears are brightly quenched without oxidation in the front chamber. In the back chamber protective atmosphere (methanol or nitrogen can be used) to achieve non-oxidative heating or carburizing in carburizing atmosphere; the middle part of the front chamber is the workpiece gas quenching chamber, the lower part is the near-gas pipeline, and the upper part is the cooling return air heat exchanger. A high-power fan with variable frequency speed regulation is installed on the outside of the front room, and the workpiece is cooled and quenched by the rapid circulation of N2 or He, and the quenching cooling speed can be controlled by adjusting the fan. The workpiece after high-pressure gas quenching has no oxidation, the surface is silver-gray, and the distortion is small, which avoids the cleaning and other processes required after oil quenching, and saves the cost of machining and the consumption of quenching oil.

(2) High pressure gas quenching and technology

It not only improves the heat treatment quality of the product (such as reducing quenching distortion, etc.), but also reduces the production cost by about 20% and avoids environmental pollution. The production line is mainly composed of loading and unloading table, front cleaning chamber, pretreatment furnace, heating furnace, carburizing furnace, diffusion furnace, high-pressure gas quenching chamber, tempering furnace, cooling table, control system, etc. High-pressure gas quenching and heating furnace on the production line There are two seals (heat seal and vacuum seal) between the two, and there is a rolling transfer system intermediate chamber between the gas carburizing chamber and the gas supply quenching pressure chamber, which can be smoothly transferred to the gas quenching chamber at a speed of less than 10s. The entrance to the intermediate chamber is made small to minimize the interference between the oxygen in the furnace and the nitrogen in the gas quenching chamber.

The process flow is: 400 ℃ preheating → 925 ℃ carburizing → 860 ℃ diffusion → 2MPa nitrogen high pressure gas quenching → 170~190 ℃ tempering.

Energy saving and consumption reduction effect. The production line combines the advantages of high-pressure gas quenching, as follows: large production capacity; high-pressure nitrogen quenching replaces traditional oil quenching, which saves the consumption of quenching oil and cleaning agent, avoids oil and gas pollution during oil quenching, and realizes clean production , eliminating the need for post-cleaning, reducing production costs by about 20%; reducing workpiece quenching distortion and reducing subsequent grinding costs.