Types and Applications of Key Connections
The commonly used types of key connections include flat key connections, semi-circular key connections, wedge key connections, and spline connections. These connection types can be divided into three types based on their structural characteristics and purposes: loose key connection, tight key connection, and spline connection.
(1) Loose key connection: ① Ordinary flat key, transmits torque by side, has good neutrality, but cannot transmit axial force; Mainly used to fix rotating parts such as gears, pulleys, sprockets, camshafts, and flywheels on shafts Half circle key: transmits small torque from the side, has good centering, and the half circle surface can adjust adaptively around the center of the circle, but cannot withstand axial forces; Mainly used for cone surface connections with small loads or as auxiliary connection devices. For example, there are many applications such as automobiles, tractors, and machine tools Guiding flat key: In addition to having the characteristics of ordinary flat keys, it can also play a guiding role; Generally used for relative axial sliding between shafts and hubs.
(2) Tight key connection: There are mainly two types: ordinary wedge keys and hook wedge keys, which transmit torque from top to bottom. The key itself has a 1:100 slope and can withstand unidirectional axial force, but with a neutral deviation; Generally used for connections that require bearing unidirectional axial forces and have less strict requirements for neutrality.
(3) Spline connection: available in rectangular, involute, and triangular shapes; Large contact surface, high shaft strength, high torque transmission, good neutrality and guidance, but high cost; Generally used in situations where good neutrality, high strength, and large torque transmission are required. Such as cars, tractors, and machine tool transmission shafts with high cutting forces.