Casting technology of nodular cast iron piston ring

Nodular cast iron piston ring plays the role of sealing, heat transfer and support in the engine, so it is required that the piston ring has good wear resistance, elasticity and thermal stability, especially for one ring. The development and application of nodular cast iron piston ring is a qualitative leap in the history of piston ring manufacturing. How to stably manufacture nodular cast iron piston rings is a difficult problem faced by the piston ring industry. In order to solve this problem, our factory has imported all the technology and related equipment of single body double piece nodular cast iron piston ring from Goetze AG, Germany.

As shown in the figure, the design guideline of single body double piece casting is to use milling cutter to mill the upper and lower surfaces of the billet which are easy to produce pinholes and slag inclusion defects, so as to obtain excellent nodular cast iron piston rings. This casting method has been widely used abroad and has rich production experience. Many domestic manufacturers have also accepted and started trial production, but it is not very successful. The main reason is that the raw material problem and the production process of nodular cast iron piston ring are too complex. It is difficult to ensure the matrix structure of nodular cast iron piston ring and the qualified rate of casting. There are many problems in the initial stage of production, such as the number of soft balls, the supply rate of hardware and so on. However, there are still many problems in the initial stage of production, such as the introduction of soft balls, which do not meet the requirements of production. After trial production and exploration, we basically mastered the production process suitable for our factory, and comprehensively solved the technical problems of nodular cast iron piston ring casting, so as to ensure the qualified rate of nodular cast iron piston ring casting. The following is a brief introduction of how our factory trial produces nodular cast iron piston rings.

In the production of nodular cast iron piston rings, the newborn iron containing manganese, phosphorus, sulfur and silicon as low as possible and very few other elements should be selected, and the appropriate spheroidizing agent, inoculant and addition amount should be selected. Secondly, under the condition of ensuring that there is qualified nodular cast iron raw liquid iron, it should have sufficiently high tapping temperature and pouring temperature, the pouring speed as fast as possible, and end the pouring within the pouring time limit specified in the process, so as to ensure the spheroidization and inoculation quality. Finally, the ability of rapid mold filling and slag retaining should be considered in the design of ring sample and gating system. Only in this way can we produce qualified castings of nodular cast iron piston rings. In addition, in order to ensure machining performance, necessary annealing heat treatment should also be carried out, which will not be introduced here.

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