Patent RU-2252267-C1 (RU)
Title: Method of production of machines and motor-cars heavy-loaded components made out of steel with lowered hardenability and a method of production of cross-pieces and trunnions made out of steel with lowered hardenability
Inventor: LOBOZOV V P
IPC: C21D9/32
Filed: 2004-03-04
Granted: 2005-05-20
Abstract: FIELD: mechanical engineering. 
     SUBSTANCE: the invention is pertaining to mechanical engineering and may be used at production of the heavy-loaded motor-car components made out of steel with lowered hardenability, for example, cylindrical and conical gears. Besides the invention also may be used in production of a cardan or a differential trunnions made out of steel with lowered hardenability. The method includes a heating up of billets for stamping, stamping, a thermal treatment of forgings, preliminary machining, a volumetric-surfacing hardening of components by their through induction heating up to the hardening temperature and the following self-tempering with cooling by a water medium and an aging in the open air and final machining. At that the thermal treatment is realized with use of the temperature of the termination of the stamping in two stages. On the first stage conduct a cyclical cooling of each forging up to temperature of beginning of release of exuberant ferrite in steel with effective cooling of the forging in the beginning of each cycle with water or air medium till reaching by an outer surface of the forging of temperature by 30-50°C below the temperature of its core and the following aging of the forging in the open air for alignment of temperature. On the second they conduct the final cooling of the forgings in the open air, make preliminary machining of each forging up to the sizes, which are less than the final sizes by a value equal to the value of their increase after the volumetric-surface hardening. After induction heating of the components in the process of a volumetric-surface hardening they conduct the components isothermal aging at this temperature, and then - a self-tempering of each component, at which after aging in the open air each component is repeatedly chilled by the water medium. The final machining of the components is made by the smooth finish of their working surfaces up to required accuracy without a change of the final sizes. At production of trunnions, after the induction heating of a trunnion for a volumetric- surfacing hardening carry out its isothermal aging at this temperature, after which close the oil ports in its tenons by plugs and carry out a self-tempering, at which after aging in the open air repeatedly chill it by a water medium. The final machining of the components is made by the smooth finish of their working surfaces up to required accuracy without a change of the final sizes. Production of the heavy-loaded motor-car components made out of steel with lowered hardenability with the help the offered method allows to increase their durability and reliability, and also to reduce cost of their production. 
     EFFECT: the invention ensures production of the heavy-loaded motor-car components made out of steel with lowered hardenability and allows to increase their service life and reliability, to reduce cost of their production. 
     2 cl, 2 tbl