Understand the processing technology of differential straight bevel gear
First, the working principle of bevel gear and the cause of wear
Straight bevel gears have been widely used in basic industries such as transportation, wind power and equipment manufacturing, and many fields because of their advantages of smooth transmission, high efficiency, strong bearing capacity and easy formation of tooth shape.
The differential gears in the rear axles of automobiles, agricultural machinery and loaders are subject to complex and variable working conditions such as heavy load and impact for a long time. If the precision of the net forming bevel gears is accurate, the machining process is carried out. Fully demonstrate and optimize, so that the positioning reference, inspection reference and assembly standard are unified in the process, ensuring that the geometrical tolerance can be stably controlled within a certain range, which can effectively improve the efficiency and precision of machining, and thus improve the use of bevel gears. Life, noise reduction and transmission stability are of great practical significance.
Ordinary car differentials generally consist of four planetary gears, a cross shaft, two differential half shells, two half shaft gears and spherical washers, half shaft gear washers and other related accessories.
The differential housing and the planetary gear cross shaft are integrated to form a planet carrier. When the car is traveling straight on a flat road surface, the four planetary gears revolve around the axis of the two half-shaft gears with the planet carrier, and the planetary and half-shaft gears are in a relatively static state.
When the car is turning, it must adapt to the need of the outer drive wheel stroke during the turning process is greater than the inner drive wheel stroke. The angular speed of the two wheels rotates differently. The four planetary gears are revolved along with the planet carrier around the two half shaft gear axes. Each of them rotates around its own axis. At this time, the bevel teeth of the planetary and half-shaft gears begin to mesh with the transmission, and the engaged single teeth are forced and transmit torque.
In the whole process, as the force of each single tooth is different (the force can be decomposed into the circumferential force and the axial force of the gear tooth surface), each gear has a tendency to deviate from the cone center to different degrees, so that the planetary and half shaft gears Press the spherical washer and the semi-axle washer separately. The two washers will rotate at the same speed or at different speeds as the gear rotates. At this time, the gasket will rub against the gear contact surface and the shell surface. Over time, the gasket will be There will be varying degrees of wear and tear.
If the gear is mounted on the taper tooth as the reference, the angular gear tolerance of the semi-axle mounting surface, the spherical surface of the planetary gear and the inner hole is seriously different. When the whole gear is in the differential working state, the two gaskets will be alternately disordered. The load accelerates the irregular wear of the gaskets.
The parts in the whole differential are the wearing parts themselves, but the end customer's car does not pay attention to the regular inspection and replacement of the wearing parts during the driving process, resulting in the gears being in need of normal wear due to the wear of the gaskets. When the meshing is in working state, the gear can not be meshed normally. The cones of the six gears will be deviated to different degrees, so that the single tooth contact areas of the gears are seriously deviated from the middle of the tooth profile and are biased toward the tooth tip and the small end. Intensified (some gasket thickness will wear half or wedge shape), which will increase the wear of the shell surface and the tooth surface. Pitting, peeling or straining will occur on the gear surface, and more serious blocks or broken teeth will appear. , causing damage to the gears.
From the above working principle of the differential gear and the description of the damage reason, it is not difficult to recognize the importance of controlling the geometric tolerance of the differential gear during machining.
