Operating conditions and performance requirements of helical bevel gears

Spiral bevel gears transmit power and change speed during working process. Rolling and sliding exist between the meshing tooth surfaces and the root of the gear teeth is also affected by pulsation or alternating bending.Under the action of various stresses caused by this, the gear will suffer from tooth breakage, tooth surface bonding, tooth surface fatigue and tooth surface wear.

The main stresses causing gear failure are friction, contact and bending stresses.According to the form and cause of gear failure, the selection of gear material and heat treatment method should be considered from the following aspects:

The gear surface has sufficient hardness.There are actually unevenness and bump on the tooth surface, so a great pressure will be generated locally, which will cause plastic deformation of the metal or insert it into the relative surface, resulting in direct contact and adhesion of the metal. When the meshing tooth surface slides relative to each other, friction is generated.

Tooth surface wear is caused by friction.The key to reducing such wear is to improve the plastic resistance of the tooth surface, i.e. to increase the hardness of the tooth surface.Increasing the hardness of the tooth surface can also improve the contact state of the tooth surface, thus improving the fatigue resistance of the tooth surface.

The core of the teeth should have enough strength and toughness to ensure that the teeth have sufficient impact resistance under variable or impact loads.

Big and small gears should have a certain degree of hardness difference to improve their glue resistance.

Consider material processability and economy.Performance requirements of spiral bevel gear. Spiral bevel gear is the main driving part of the vehicle. Active spiral bevel gear transmits power from the vehicle transmission to the driven bevel gear, which then transmits power to the differential.

Therefore, in part structure, the active spiral bevel gear is a gear shaft, one end is spline, which connects with the power output shaft of the transmission and the other end is a spiral bevel gear; the driven bevel gear is a disc gear with a diameter larger than the active spiral bevel gear, so as to reduce speed. At the same time, some bolt holes are distributed around the circumference so that the driven bevel gear is fixed on the differential housing by bolts, so as to drive after deceleration.Force is transmitted to the differential.

Driven bevel gears not only have high transmission speed, but also transmit high torque, and they also bear impact load when loading and braking.The main failure modes of this type of gear are wear, pitting and fracture.Therefore, driven spiral bevel gears should meet the following performance requirements:

(1) Good mechanical properties;

(2) Good carburizing and quenching properties;

(3) Good impact resistance;

(4) Good heart hardness;

(5) Good thermal deformation properties.