Forging crankshaft strength and stiffness

- Jul 13, 2018 -

Forged crankshafts are very important components in the engine during operation. To a certain extent, they are mainly subjected to the force transmitted from the connecting rod, effectively converting it into torque through its crankshaft output and driving other accessories on the engine. The crankshaft is subjected to a centrifugal force of a rotating mass, a cyclically varying gas inertial force, and a reciprocating inertial force to cause the crankshaft to undergo a bending torsional load.

The forged crankshaft requires the crankshaft to have sufficient strength and rigidity to a certain extent. The journal surface needs to be wear-resistant, work evenly, and has good balance. In order to reduce the mass of the crankshaft and the centrifugal force generated during the movement during operation, The crankshaft journal is often made hollow. Oil holes are formed in each journal surface to introduce or withdraw oil to lubricate the journal surface. In order to reduce the stress concentration, the transition of the main journal, the crank pin and the crank arm is connected by a circular arc.

The balance weight of the forged crankshaft is mainly used to balance the rotating centrifugal force and the moment. The advantage of the forging can also effectively balance the reciprocating inertial force and the moment. When these forces and moments reach their balance, the balance weight can also be used to reduce the main bearing. The load. The number, size and placement of the counterweights should be considered based on factors such as the number of cylinders in the engine, the arrangement of the cylinders, and the shape of the crankshaft. The balance weight is generally integrated with the crankshaft casting or forging. The high-power diesel engine balance weight is manufactured separately from the crankshaft and then bolted together.