Fatigue analysis of hardened gear reducer

Hard-tooth surface reducers are mostly used in the light textile machinery processing industry. This year, metallurgical enterprises have also gradually adopted them. They are used more in the material belt conveying process, and are used less as the main reducer of the rolling mill train in the steel rolling equipment.Therefore, the bearing capacity of the reducer is not only limited by the mechanical strength power and the allowable power of thermal balance, but also pays special attention to the operation of the machine and the harsh environment. When selecting this type of reducer, the environment, temperature, load should be considered. The influence of factors such as variability.

The fatigue cracking of the rack occurred in the gear pair of the low-speed stage. The meshing condition of the entire gear was investigated (taking one in January 1997 as an example), and it was found that the meshing gear showed a large area of ​​pitting due to the failure of touch fatigue, mottled and densely covered, and the width of a single etch pit It is 1~10mm, during which the center transition gear shaft falls off 15 (No. 2, No. 1) The low-speed shaft large gear falls off 2 (No. 2, No. 3).The cracking condition of the four racks that fell off was investigated. No. 4, 2, and 3 were dark gray stubborn fibrous fractures, and there were significant indentations on the meshing pitch circle. It was analyzed that the No. 4 rack fell off first, and kneading caused No. 1 and No. 2 racks are passively cracked, and the fracture is the normal fracture arrangement of the fatigue failure and broken teeth caused by overload operation.The surface of the No. 3 rack is light gray, smooth and shiny, and the broken tooth is a cleavage fracture of transgranular cracking, which is an abnormal brittle fracture.

After analysis, it is believed that the reason for the fatigue and damage of the hardened gear reducer is that one is due to the quality problems in the processing and manufacturing process of the reducer; the other is that the selection of process equipment is wrong, and the thermal power cannot meet the requirements of the production process, forming a practical operation process. The medium load is large, and the shadowing defects are gradually exposed, resulting in the contact fatigue and damage of the final gear, the rack falling off and cracking, and the equipment being scrapped. Therefore, the selection of the rolling mill hardened reducer is prudent.