Process for producing large-scale diesel engine cam workpiece with high hardness and abrasive resistance

Abstract

The invention discloses a process for producing a large-scale diesel engine cam workpiece with high hardness and abrasive resistance. The process comprises steps of blank forging, annealing, coarse machining, carburization and high-temperature tempering, semi-finish machining, quenching and low-temperature tempering, and finish machining; and the step of the carburization and high-temperature tempering comprises the following steps: after completing the carburization of the cam workpiece, reducing the temperature of a furnace to the temperature of between 890 and 910 DEG C; performing oil quenching after keeping the temperature for 30 to 45 minutes, and rapidly cooling the cam workpiece; and putting the cooled workpiece in the furnace at the temperature of between 610 and 650 DEG C for high-temperature tempering, wherein the tempering time of the high-temperature tempering is 2 to 4 hours. The surface hardness and the abrasive resistance of the cam workpiece manufactured by the production process are greatly improved. The production process can also further comprise the step of sulphur and oxygen combining treatment, improve the lubrication of the cam workpiece, and reduce a friction factor of the surface of the cam workpiece.

Description

technical field [0001] The invention relates to a production process of a large diesel engine cam workpiece, in particular to a production process of a large diesel engine cam workpiece and a roller workpiece with high hardness and high wear resistance. Background technique [0002] Cam workpieces and roller workpieces are important parts of large diesel engines. In diesel engine equipment, wear failures of cam workpieces and roller workpieces often occur. Failures of adhesive wear and contact fatigue wear account for a large proportion of failures in mechanical engineering. And as the diesel engine becomes larger and stronger, the technical requirements for the friction pair of the corresponding cam workpiece and roller workpiece are also higher. [0003] The production process of the cam workpiece in the prior art generally includes blank forging, annealing, rough machining, carburizing and high temperature tempering, semi-finishing, quenching and low temperature tempering...

AI Technical Summary

Problems solved by technology

[0004] The carburizing and quenching method of the low-speed diesel engine cam mentioned above, because the carbon potential is not high, the carbon content of the carburized layer on the surface of the cam workpiece is not high, and the low carbon content cannot ensure that the cam workpiece will form a large amount of needle-shaped carbonization in the subsequent process However, high carbon content and a large number of needle-like carbides on the surface are the necessary metallographic structure to ensure the high hardness and high wear resistance of the cam workpiece. In the above-mentioned patent application, the carbon content of the carburized layer is not high, so after quenching The carburized layer after low-temperature tempering can only form the structure of cryptoneedle martensite + a small amount of retained austenite, without needle-like carbides, and the surface hardness of the cam workpiece is only 58-62HRC, which is not high in hardness and wear resistance Not high, the cam workpiece often scratches or bites after a few hours of use during use, or often wears quickly during early use and leads to scrapping

[0005] If the conventional process also adopts high carbon potential carburizing for the cam workpiece, new problems will arise. During the high carbon potential carburizing process, due to the accumulation of carbides, the precipitation of network carbides will occur during the cooling process after carburizing, and The carbon content of the carburized layer is reduced, which reduces the hardness and wear resistance of the cam workpiece, which will cause excessive residual austenite in the subsequent quenching process, making the hardness of the cam workpiece not meet the requirements, resulting in Unqualified products or affect the performance of the workpiece

[0006] At the same time, the lubricating performance of the cam workpiece in the prior art is poor, the friction coefficient of the friction pair is high, and the cam workpiece has no self-protection function when sliding friction occurs during the running-in phase and during operation, resulting in a reduced service life of the cam workpiece and easy damage