What are the common failure forms of gear meshing transmission?

The failure of gear meshing transmission mainly refers to the failure of gear teeth. Due to the different application occasions, working conditions, gear materials and heat treatment processes of gear meshing transmission, there are many failure forms, but the common failure forms are as follows.

(1) Tooth fracture

In operation engineering, the load borne by the gear is like a cantilever beam. When the periodic stress of the pulse exceeds the fatigue limit of the gear material, it will produce cracks at the root and gradually expand. When the rest can't bear the transmitted load, it will break the teeth. In the process of working, gear teeth may break due to severe impact, unbalanced load and uneven material.

(2) Fatigue pitting of tooth surface

When two meshing gears contact, the force and reaction between tooth surfaces cause contact stress on two working faces. Because the position of the meshing point changes and the gear moves periodically, the contact stress changes according to the pulse period. Under the action of this alternating contact stress for a long time, small cracks will appear at the tool mark of the tooth surface. With the passage of time, this kind of crack will gradually spread laterally on the surface layer. After the crack forms a ring, the surface of the gear tooth will peel off in a small area, forming some fatigue shallow pits.

(3) Tooth surface wear

For open gear transmission or closed gear transmission with unclean lubricating oil, some hard abrasive particles enter the friction surface due to the relative sliding between meshing tooth surfaces, which changes the tooth profile and increases the backlash, making the gear excessively thin and broken. Under normal circumstances, only when abrasive particles are mixed into lubricating oil will the abrasive particles on the tooth surface be worn during operation.

(4) Tooth surface gluing

For high-speed and heavy-load gear transmission, due to the large friction between tooth surfaces, high relative speed and high meshing temperature. Once the lubrication condition is not good, the oil film between the tooth surfaces will disappear, making the metal surfaces of the two teeth directly contact and bond with each other. When the two tooth surfaces continue to move relative to each other, the harder tooth surface tears off some substances on the softer tooth surface along the sliding direction, forming grooves.

(5) Plastic deformation of tooth surface

Under the impact load or heavy load, the tooth surface is prone to local plastic deformation, thus deforming the involute tooth profile surface.

Meshing refers to a transmission relationship between two mechanical parts, which is called meshing transmission. Gear transmission is the most typical meshing transmission and the most widely used transmission form. According to the different transmission principles, there are spur gear meshing transmission and helical gear meshing transmission. Gear meshing transmission has the characteristics of wide application range, high transmission efficiency, long working life, stable transmission, high reliability, constant instantaneous transmission ratio, and can realize two-axis transmission with various position requirements, which is widely used in modern mechanical transmission. It consists of a driving gear, a driven gear and a frame. Through the meshing action of gears, the motion and power of the driving wheel (shaft) are transmitted to the driven wheel (shaft), and the required speed and torque are obtained.