Nodular cast iron piston rings are more and more widely used in various engines such as agricultural machinery, automobiles and cars, mini cars and motorcycles Φ one hundred and ten Φ one hundred and fifteen Φ 120 and other single cylinder diesel engines, 4 102, 4 105, 6 110, 6 126, 6 130, 6135 and other multi cylinder diesel engines. In addition, the first gas ring in the supercharged multi cylinder diesel engine, The second gas ring and even the lower oil ring also use nodular iron rings. “These are because nodular iron piston rings have high strength, high thermal stability, excellent wear resistance, melting wear resistance and long service life after chromium plating and key spraying treatment.
(l) Ductile iron ring blanks include single elliptical, double elliptical sand casting and various cylinder casting methods), such as manual sand casting, Guangyang or di sand automatic molding, vertical parting, non box sand casting, centrifugal cylinder casting and lost foam cylinder casting.
(2) The single piece ring is only applicable to the nodular iron ring of motorcycle mini car with small cylinder diameter. Due to its low process yield, it can only be produced conditionally after digesting and treating most of the returned materials.
(3) The cylinder ring is generally cast in a round cylinder, or it is difficult to popularize and apply the cylinder ring process in the future due to low casting productivity, restrictions on production varieties, shrinkage defects in the center, or difficulties in slicing due to too large machining allowance.
(4) Because of its small machining allowance and high casting productivity, double piece elliptical casting can be produced with 24145 or high-pressure molding machine. The slicing is relatively simple. There is no shrinkage defect in the single ring after slicing, and it can be processed by copying the inner and outer circles. It is a better production method, In the future, the main piston ring manufacturers in China will basically adopt this advanced.
(5) Based on double piece elliptical casting, four pieces of elliptical blanks are produced by high-pressure molding machine, so as to greatly improve the casting production efficiency and reduce the casting production cost. This casting method is the development direction in the future. Of course, it is necessary to design and manufacture high-efficiency slicing machine tools to match it.
There are various casting methods for the blank of nodular cast iron piston ring, such as single piece elliptical sand casting, double piece elliptical sand casting, cylinder manual sand casting, automatic molding production line sand casting, centrifugal cylinder casting and lost foam cylinder casting. These casting methods, their advantages and disadvantages and the development direction in the future are introduced and discussed.