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Bearing heat treatment technology and equip ‘ Four)

31st July 2013 Bearing Technology 0 Comments

3.The isothermal quenching of bainite is equipped

According to characteristic that the bearing is processed, mainly there are two major kinds of apparatuses used: Automatic production line and cycle stove.

1Automatic production line variety little suitable for automated production by the intersection of batch and loud bearinging, if the production of the bearing of the railway use more automatic production lines. The automatic production line is mainly made up of controlled atmosphere oven and isothermal quenching trough, among them some used apparatuses of isothermal quenching can be divided into three kinds according to transporting the movements of the work piece: Transferring to the bottom type, calculating disc type and sending ribbonly. It is to put transferring to the bottom or calculating disc organization in isothermal salt bath that the ones that are loved the forest company of the association to develop transfer to the bottom type, push the disc isothermal quenching apparatus, the work piece is passed in and out according to certain beat, memory controls the order discharging, movements are by PLC program control. This kind of apparatus automaticity is high, but investment is great.

2Because cycle type isothermal quenching apparatus rolling mill bearing is wide in variety, the batch is little, the medium and small-scale rolling mill bearing manufacturer adopt more box furnaces or well-type stoves quench the cooling tank isothermal trough cleaning tank, also adopt the box furnace a plurality of isothermal troughs. It is with little investment that this is disposed, the suitability is strong, but labor intensity is great, the safety is bad. At present, when the isothermal quenching of bainite is popularized in a more cost-effective manner, have use in the minor rolling mill bearing of load and already been succeeded in getting application in China the carburizing steel by the isothermal quenching of bainite.

4.Controlled atmosphere and control

With the improvement of surface qualitative requirement after quenching to the work piece, it is controllable to protect It is popularized that the atmosphere heat, does it protect or controllably to include annealing and adopt in the inner heat treatment The atmosphere is heated. In the seventies of the 20th century, mainly adopted and sucked the heating type atmosphere. It sucks heating type atmosphere to be the intersection of raw materials and angry pneumatic mist part react, take shape first kind suck under function of catalyst? CO 18%- 23%? H2 37%- 42%, controlled atmosphere of excess N2, there is application in the field of Chinese bearing heat treatment in this kind of atmosphere. It is the widest that the heat treatment in the field of Chinese bearing of propane atmosphere of nitrilo is quenched and employed on the line, the components and sucking the heating type atmosphere closely of the atmosphere of nitrogen methanol, the atmosphere of nitrilo represented by nitrogen – methanol is employed more on the net belt stove. In the 1990s, led air and hydrocarbon to higher than the inner gas producing method of 800 ℃burner hearth directly, namely the growing atmosphere directly. Through the finding, this kind of atmosphere which contains the high CH4 composition, though its gas reacts and can not be similar to the equilibrium intensity which sucks the heating type atmosphere, but the transmitting capacity of its carbon is controlled by CO and content of H2 in atmosphere, combining CO2 analysis meter with oxygen probe is controlled and can be realized carbon tendency. The major advantage of the growing atmosphere is to save the angry consumption of raw materials in a large amount directly, according to statistics no matter this kind of atmosphere is used in the cycle type atmosphere stove or continuity atmosphere stove, its raw materials are angry to consume and save reachable about 70% of expenses. Today, many kinds of heat treatment that nearly 300 multi set of atmosphere stoves use this kind of atmosphere to quench cementation, carbonitriding and controlled atmosphere in the whole world,etc.. The growing atmosphere is employed in the field of cementation more in the field of Chinese bearing directly.

The real application in recent years shows, the life time of oxygen probe is not so definite, the difference between oxygen probe metric carbon tendency and actual value is unpredictable. So controlled atmosphere because the intersection of oxygen and probe fail uncontrolled sometimes, lead to the fact and decarbonizate the defect of oxidizing etc.. China often adopts its survey accuracy of fixed check-up at the present stage, is unfavorable to the stove and realize full automatization, will even influence the normal production sometimes.

In view of the above-mentioned reason, has developed a double measuring system abroad, standard oxygen probe of a strip among them is used in normal control carbon tendency, another independent measuring system is used for measuring the operating condition of this oxygen probe, namely these two systems measure carbon tendency of the atmosphere separately, as the result appears at the time of the deflection greatly, will call the police. It can be CO2 infrared analysis meter that the second measures the system work component, it can be a miniature oxygen probe λ – probe too . Up until now, a lot of atmosphere stoves have installed such double measuring system already.

Take a broad view of whole, Chinese bearing heat treatment technology and equip, have greatest elongation very much than developed country, especially annealing and equipping disparity bigger. Other trades have certain distances to heat treatment technology and equip with bearing, improving the bearing quality concerns the development of the equipment manufacture of China.

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