Fatigue Analysis of Hardened Gear Reducer

Hardened gear reducers are mostly used in the light textile machinery processing industry. This year, metallurgical enterprises have also gradually adopted them. They are mostly used in the raw material belt conveying process, and are used less as the main reducer of the rolling mill train in the 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 must pay special attention to the operation of the machine and the harsh environment. When selecting this type of reducer, the environment, temperature, The influence of factors such as variable load.

The fatigue fracture of the rack occurred in the gear pair of the low-speed stage, and the meshing condition of the entire gear was observed (taking one time in January 1997 as an example), and it was found that the meshing gear had a large area of ​​pitting due to contact fatigue failure, with dense spots and individual etch pit widths. It is 1~10mm, and 15 pieces of the intermediate transition gear shaft (No. 2 and No. 1) are peeled off from the low-speed shaft large gear (No. 2 and No. 2).Observe the fracture of the four racks that have been peeled off. No. 3, 4, and 2 are dark gray willful fibrous fractures, and there are obvious indentations on the meshing pitch circle. It is analyzed that the No. 3 rack is peeled off first, and extrusion causes 4, 1 , No. 2 rack is passively fractured, and the fracture is the normal fracture structure of the fatigue failure 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 fracture, which is an abnormal brittle fracture.

Through analysis, it is considered that the reasons for the fatigue damage of the hardened gear reducer are: firstly, due to the quality problems in the processing and manufacturing process of the reducer; secondly, the selection of the process equipment is wrong, and the thermal power cannot meet the requirements of the production process, resulting in the actual operation process. The medium load is large, and the hidden defects are gradually exposed, resulting in contact fatigue damage of the final gear, peeling and breaking of the rack, and scrapping of the equipment. Therefore, the selection of the rolling mill hardened reducer must be careful.