Some gear parts transmit motion and load through the connection between the gear hub and the shaft. The shape, size and position of the gear hub will directly affect its carrying capacity and the positioning accuracy of the gear parts as a whole and the shaft. What should be paid attention to when designing the gear hub ?

    (1) The gear hub should have an appropriate width in the axial direction

    The wheel hub realizes the radial positioning of gear parts through the coordination of the hole surface of the wheel hub and the shaft.In order to ensure sufficient positioning accuracy and load-bearing capacity, the width of the gear hub should not be less than the tooth width.For gear parts with large axial forces such as bevel gears and worm gears, the width of the hub should be larger, and its width should be determined according to the diameter of the shaft.

    (2) The gear hub should have a certain thickness in the radial direction

    Commonly used key and interference coupling between gear hub and shaft.In order to ensure the connection strength and load-bearing capacity, the gear hub needs to be thick enough.The thickness of the hub can usually be determined based on the diameter of the shaft.When a solid structure gear is connected by a key, the keyway on the hub hole weakens the strength of the gear hub, so the remaining thickness of the hub should also meet certain requirements. If the remaining thickness value does not meet the requirements, the gear and shaft should be made It is inconvenient to process gears with an integrated structure, and if the gear fails, it will be scrapped at the same time as the shaft. Therefore, when the remaining thickness value meets the requirements, the gear and shaft should be designed as an integrated structure.

    (3) The gear hub, flange and web should have a reasonable relative position.

    Usually the hub is arranged symmetrically with the rim and web, but sometimes the hub can also be offset. Some sprockets, when the transmitted load is small, are connected with the shaft by a set screw, so the gear hub is designed as an offset structure. When uneven load distribution occurs in the tooth direction, if the web is biased to the side with less force, the rigidity of the gear teeth on the side with the greater force decreases, which is beneficial to change the force of the gear teeth. For parts that are fixed in the direction, the hub is usually biased toward one side of the axial force. For example, solid and web bevel gears use pulley hubs with different bias directions. The moment fulcrum of the pulley is close, and the shaft is stressed. Better, the structural hub with less rigidity on the left side can reduce the stress concentration generated by the interference fit of the hub, and the fatigue strength of the state is better.

    (4) Pay attention to the design of the end face of the wheel hub

    The assembly position of gear parts on the shaft is often limited by the shaft shoulder, which means that the end face of the pillow hub and the end face of the shaft shoulder are in good contact. In addition to a certain perpendicularity requirement relative to the center line of the hub hole, the end face of the hub should also have less roughness Degree value.Important parts such as gears and worm gears have specific regulations in the corresponding standards.