1. The function and type of gear
Gear transmission is an important part of mechanical equipment, which has the functions of transmitting power and changing direction.
Types of gears: According to the mutual position of gear transmission axes, it can be divided into three categories-parallel axis transmission, intersecting axis transmission and staggered axis transmission.
2. Working characteristics of gears
Different types of gears have different working characteristics. For example, in spur gear transmission, the tooth surface contact line is a straight line parallel to the axis. The meshing of the gear teeth is to contact or separate at the same time along the entire tooth width, so it is easy to cause shock And noise.
Gear working conditions
With the rapid development of modern industry and the emergence of special, heavy, high-speed, and heavy-duty equipment, the transmission conditions of gears are becoming more and more demanding, especially in the automotive industry and aviation industry. The reduction box and transmission box of other general industrial gear devices Working conditions are more relaxed. In a word, under different operating conditions, the gear tooth surface meshing pressure, gear circumferential speed and grease temperature at work are quite different. The gear tooth surface meshing load pressure is 0.8～4Gpa, the gear circumferential speed It is 5-100m/s, and the grease temperature during operation is between 40-200℃.
Three, the damage of the gear
(1) The form of gear damage
Gear damage can be divided into four types: adhesive wear, abrasive wear, fatigue wear, and corrosion wear. The above four types of wear are manifested under different working conditions (torque and speed, etc.)
(2) The main reason for damage
When the friction pair is in operation:
1. The lubricating grease has low viscosity, too low speed, and too much load to build an grease film
2. Different degrees of adhesive wear caused by excessive peripheral speed, excessive load, sliding rolling, poor quality grade of lubricating grease, improper viscosity, lack of grease, etc.
3. Particles such as external dust and other impurities mixed into the lubrication system, as well as internal wear debris, colloid and other impurities, cause particle wear.
4. Under the repeated action of the cyclic contact stress, the gear will be fatigued and worn, and the surface material will be pitted, peeled and broken;
5. Water, metal particles, chemical pollutants, and the chemical action of lubricating grease and the participation of oxygen in the lubrication system cause corrosion and wear.
In short, gear damage is caused by the interaction of sliding, rolling, impact, lubricating materials and other media with the friction pair during the operation of the gear, such as scratches, pitting, and fracture.
Fourth, the lubrication of gears
The main quality performance requirements of gear lubricants:
1. Proper viscosity and good viscosity-temperature performance; the viscosity should not be too low to form a thick enough grease film, but the viscosity should not be too large, so as not to be easy to start at lower temperatures.
2. Good extreme pressure performance: for hyperbolic gears, curved bevel gears, helical gears, and worm gear transmission gears, they are in line and point contact, bear heavy load and high speed, and have both sliding and rolling. It is very demanding, so it must have good extreme pressure performance.
3. Good anti-oxidation stability: The working temperature of the grease is very high during the high-load and high-speed operation of the gear, and it is easy to oxidize and deteriorate. Therefore, the gear grease should have good anti-oxidation stability at high temperatures.
4. It has good anti-corrosion performance: during the operation of the gear, due to the effect of oxidation and additives, the tooth surface is corroded, and the gear is easy to rust with the participation of water and oxygen. Therefore, the gear grease should have good anti-corrosion Rust performance, etc.