Quality problems in gear quenching

by:Hengyang Furnace     2021-01-09
Insufficient hardness and enough hardening depth quenching cooling rate is low gear quenching hardness is insufficient, the reason of uneven hardness and hardening depth is not enough, however, according to the actual gear quenching material, shape, size and heat treatment requirements, and can be divided into high temperature stage of insufficient cooling speed and cooling speed in low temperature stage and different situation such as insufficient cooling speed and low temperature stage. For example. For medium and small gear, inadequate quenching hardness, is often cold speed due to insufficiency of high temperature stage, in the big modulus gear requires deep hardened layer, improve the low temperature cooling rate is very necessary. 1, for quenching oil, said the general, oil steam temperature in membrane phase is short, fast speed, and low temperature cooling speed, often can obtain high and uniform quenching hardness and enough hardening depth. Workpiece loading up on quenching cooling effect has obvious influence. To make the quenching oil flows unobstructed, and equipped with and using of mixing device, can obtain the better effect. Increase the speed of the cryogenic cooling of quenching medium used, often can increase the depth of hardening layer. Under the condition of the same layer carbon concentration distribution, low temperature cooling rate higher quenching oil, often get deeper quench hardening layer, therefore, the cooling speed of quench oil, can shorten the carburizing time of artifacts accordingly, also can achieve the required quench hardening layer depth. Requirements of carburizing and hardening layer depth, the greater the the effectiveness of the method shorten the carburizing time is, the more obvious. 2, quenching, middle of the back of high hardness of this kind of problem may be related to the selected medium cold speed too fast or medium low temperature cooling rate is too high. One solution is to change the quenching oil to meet the requirements. The second way is contact with quenching medium manufacturers, about to add proper additives to reduce the cooling rate of quenching oil in low temperature. The third way is to switch to a lower hardenability of steel. 3, quenching deformation quenching distortion make a heartbreaker many factories. According to the habits, deformation are usually involve multiple departments to resolve the problem, the solution is often comprehensive measures. Recently published about quenching distortion, the causes of deformation mainly due to insufficient cooling speed and uneven cooling, and based on this put forward to improve the cooling speed and try to realize the principle of the solution of the homogeneous cooling method, reference [ 1] 。 Efforts to improve the quenching cooling rate is also listed in the references, the application of the same direction as long as a reasonable choice measures. Most gear quenching distortion problem can be resolved. Gear internal spline hole deformation, for example, are usually selected high temperature quenching oil cooling speed is insufficient, steam or oil membrane phase too long. Improve the oil of high temperature and cooling speed during the cooling process and improve oil cooling speed, deformation of spline in general can solve a problem. For small and medium-sized gear, especially more precision gear, choose to use good isothermal step quenching oil is to control the deformation of essential measures. 4, the problem of cracking of the gear problem, mainly appear in induction heating quenching. Choose good water-based quenching medium, such as class PAG quenchant (generally used at home and abroad Such as Beijing holley today yu 8 - fine chemical company 20, etc. ) Was used to replace the use of tap water, the problem was solved. Induction heating quenching medium using PAG. Can get high and uniform quenching hardness and depth of hardening layer and stable, quenching crack with low risk. 5, light has this aspect demand, should choose bright quenching oil or fast bright quenching oil. Often the good light bright quenching oil, cooling speed is high enough, and the cooling speed is high brightness of quenching oil is not good enough. In addition, the light of hot oil also less commonly, can change new oil or adding to improve light additives.
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