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易游游戏官网 develops new forging method for built-up crankshafts used in ship engines

August 2, 2013

易游游戏官网, Ltd. has developed a new die-forging method to manufacture built-up type crankshafts for diesel engines in ships. The new die forging method offers considerable improvements in design fatigue strength in comparison to the conventional “bending forging” method. Using the new method, 易游游戏官网 can make near-net-shape forgings for crank throws.

Due to requests to improve fuel consumption stemming from stricter environmental regulations and the high price of ship fuel, the need for “eco-ships” is rising. Two important points in the development of eco-ships are ship development to reduce drag on the hull and 易游游戏官网ine development to improve fuel consumption and lower exhaust gas emissions.

In engine development, ships are using larger propellers that rotate at slower speeds, driving the need for low-rpm propellers 易游游戏官网th high output. To meet this trend, long-stroke engines are gro易游游戏官网ng in popularity. When long-stroke engines are used, the crank throws are longer and heavier than conventional ones, leading to higher load stress on the crankshaft and higher bearing loads.

Kobe Steel has recently developed a new die-forging method using its experience as an integrated crankshaft manufacturer covering all processes of steelmaking, forging, machining and inspection. Incorporating the new forging method and techniques of clean steelmaking, Kobe Steel has successfully increased the fatigue strength of the crankshaft material by 20 percent, compared 易游游戏官网th conventional forging. As a result, long-stroke crank throws of higher reliability and lighter weight can now be commercially mass produced.

Along 易游游戏官网th the development of the new die-forging method, Kobe Steel developed automatic ultrasonic inspection technology and numerical inspection technology that digitally evaluates the part where the crankshaft touches the bearing. These technologies provide substantial improvement on the reliability of the crankshafts, which face higher load stress and bearing loads when used 易游游戏官网th long-stroke engines.

In addition to the new die-forging method, 易游游戏官网 conducts research and development of advanced materials for marine parts. Responding to customer needs, 易游游戏官网 is contributing to the advancement of the shipping and shipbuilding industries.

Background Notes

Stricter environ易游游戏官网ntal regulations

The International Mariti易游游戏官网 Organization, a special agency under the United Nations, adopted 易游游戏官网asures in 2011 to reduce the amount of CO² gas emissions from ships under the International Convention for the Prevention of Pollution from Ships (MARPOL). From 2013, the new regulations affect all construction contracts for new ships 易游游戏官网th 400 gross tonnage and above.

Construction contract year	Reduction target until 2014 for contracted vessel construction us易游游戏官网g average CO2 exhaust emission volu易游游戏官网 as the standard
2015-2019	-10% or mo易游游戏官网
2020-2024	-20% or mo易游游戏官网
2025 and beyond	-30% or mo易游游戏官网

Long-stroke 易游游戏官网ines

Refers to the ratio of the piston stroke to the cylinder bore dia易游游戏官网ter. The longer the bore/stroke ratio, the higher the efficiency.

Crank 易游游戏官网row

The throw is the offset arm on a crank to which the connecting rods to the 易游游戏官网ine are attached.