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Conditioning of hollow piston rod during machining
Apr 04, 2018

Since the hollow piston rod needs to bear a large tensile stress during the work process, the piston rod must have sufficient strength, rigidity and toughness. At the same time, due to abrasive wear during use, it is easy to produce wear. The hollow piston rod must also have high wear resistance.


At present, during the production process, hollow piston rods are usually made of 45 steel materials. The processing process can be summarized as: forging materials (rolling materials) - cutting - conditioning - straightening - machining - surface hardening, Tempering - Straightening - Head Welding - Machining - Grinding - Stress relief annealing - Polishing - Hard chrome plating - Polishing - Cleaning - Assembly.


In the above processing, the quenching and tempering process also belongs to a very important link. The purpose of the quenching and tempering treatment is to make the hollow piston rod have the comprehensive mechanical properties of good matching of strength, hardness, plasticity, and toughness, so that the internal structure of the piston rod is transformed into a uniform and fine tempered sorbite body, ready for subsequent surface quenching.


In the process of quenching and tempering, we first need to determine the basic size parameters of the hollow piston rod, and we must select the appropriate heating equipment, and at the same time control the selection of appropriate heat treatment process parameters. In order to obtain a uniform effect, quenched heating can be performed using a hanging continuous heat treatment furnace.


In this way, in the process of quenching and tempering the hollow piston rod, it is also possible to refine the grain and reduce the deformation as much as possible. We adopt a sub-temperature quenching process of 790±10°C to refine the austenite grains and obtain fine grains after quenching. Uniform lath martensite to enhance the toughness of the piston rod.


It is also necessary to add an appropriate amount of quenching additives. The purpose of this is to reduce the distortion and to further enhance the cooling of the quenching liquid to achieve homogeneity. After the above process is improved, the internal structure of the hollow piston rod is even and fine tempered sorbite, and the massive or reticulated ferrite and Widman's structure are eliminated, and the hardness of the hollow piston rod is uniform and stable.http://www.xhychromerod.com/