Do You Know The Crankshaft As The Heart Of An Engine?

The crankshaft is one of the most typical and important parts in an engine. Its function is to convert the gas pressure transmitted from the piston and connecting rod into torque, output work as power, drive other working mechanisms, and drive the auxiliary equipment of the internal combustion engine to work. This means severe acceleration and deceleration, accompanied by high bending deformation, high torque, and vibration shocks, resulting in very high and variable stresses. Such extreme stresses require careful design and calculation, selection of suitable materials, and batch processing techniques. These stresses are concentrated at the fillet radius between the support journal and the balance weight web as well as on the oil hole, so special attention needs to be paid to the machining of these locations.

Structure and material of crankshaft

The crankshaft is a slender rod, mainly composed of a main journal, a connecting rod journal, an oil seal journal, and a gear journal. There are oil holes in the main journal and the connecting rod journal, and threaded holes are provided at both ends.

According to the structure of the engine, the crankshaft mainly includes in-line and V-shaped crankshafts. The above figure shows an in-line crankshaft. The main journal is used to support the entire crankshaft. The connecting rod journal is connected to the connecting rod, driving the connecting rod piston to reciprocate up and down according to the working condition of the engine.

Commonly used materials for crankshafts include ductile iron and alloy steel. For gasoline engine crankshafts and small diesel engine crankshafts, due to their low power, the crankshaft blanks are generally made of ductile iron and high-quality carbon steel. Common materials include QT700-2, 45 steel, etc; Medium and heavy duty diesel engine crankshafts are generally made of alloy steel, commonly used materials include: 48MnV, 35CrMo, etc.

Crankshaft is an important component in an engine. Due to its complex structure, poor rigidity, and high technical requirements, the processing process is difficult, and its processing quality directly affects the technical performance and life of the engine. Moreover, as a slender rod part, it is extremely prone to deformation during processing, which requires that when designing the processing process, the crankshaft should comprehensively Fully consider the processing plan.