Hardware Knowledge Base: "Links"

Link

Two ends of the link mechanism are respectively hinged to the driving and driven members to transmit the motion and force. For example, in a reciprocating piston type power machine and a compressor, a connecting rod is used to connect the piston and the crank. Most of the connecting rods are steel parts. The cross section of the main part is mostly round or I-shaped. There are holes at both ends. There are bronze bushings or needle roller bearings in the holes for the hinge pins to be assembled. The connecting rod is an important part of the automobile engine. It connects the piston and the crankshaft. Its role is to convert the reciprocating motion of the piston into the rotational motion of the crankshaft and transmit the force acting on the piston to the crankshaft to output power.

In addition to the pressure generated by the gas in the combustion chamber, the connecting rods are also subjected to vertical and horizontal inertial forces during operation. Therefore, the connecting rod works in a complex stress state. It is subject to alternating tensile and compressive stresses and bending stresses. The main damage types of connecting rods are fatigue fracture and excessive deformation. The site of fatigue fracture is usually three high stress areas on the connecting rod. The working conditions of the connecting rods require that the connecting rods have higher strength and fatigue resistance; they also require sufficient rigidity and toughness. In the traditional connecting rod processing technology, quenched and tempered steels such as 45 steel, 40Cr or 40MnB are generally used. However, the processing technology for conrod fracture splitting widely used abroad now requires brittleness and high hardness. Therefore, the new connecting rod materials produced by German automobile companies are C70S6 high-carbon microalloyed non-quenched and tempered steel, SPLITASCO series forged steel, FRACTIM forged steel and S53CV-FS forged steel (all of which are German din standards). Although the alloy steel has high strength, it is sensitive to stress concentration. Therefore, strict requirements must be placed on the shape of the connecting rods, excessive fillets, etc. The quality of the surface processing should also be taken into account to improve the fatigue strength. Otherwise, the application of high-strength alloy steels cannot achieve the expected results.