The girth gear is the main transmission component of the rotary kiln and ball mill. As the rotary kiln and the ball mill are large-scale equipment, the girth gear often wears during operation, and is one of the accessories that need to be replaced regularly. The poor lubrication conditions in operation, the harsh working environment, and the mixture of dust, sand, and other impurities in the lubricating oil or grease, will exacerbate the wear of tooth surfaces.

Some girth gears have a service life of only about a year and a half and the life of the pinion gear is even shorter. Sometimes it needs to be replaced within three months, seriously affecting normal production. Therefore, in order to increase the service life of with large diameter, difficult casting process and long production period, it is necessary to increase the hardness of the tooth surfaces and increase the wear resistance in addition to the reasonable selection of materials.

The designed life of the rotary kiln girth gear is generally 10 to 15 years, but actually most of the girth gears only work 8 to 10 years. The pinions wear faster and their life is generally 3 to 5 years, especially for dry and semi-dry cement kilns. CHAENG (Xinxiang Great Wall Cast Steel Co., Ltd.) adopts gear surface quenching method, which significantly increases the hardness of the tooth surface and nearly doubles the service life.

Surface quenching should pay attention to:

1. It is not suitable to remove the girth gear for the quenching, otherwise, after the re-installation, the contact will be not good because of gears deformation due to quenching;

2. Keep oxygen, acetylene and water pressure unchanged during quenching;

3. The speed of movement should be appropriate. Too slow moving speed will burn the tooth surface and too fast speed will cause insufficient hardness.

4. The water pressure of the water spray should not be too high, otherwise the flame will be extinguished;

5. During operation, the beginning of each tooth should be heated for a period of time more, and the end of the tooth should be moved more quickly; otherwise, the end of the tooth can be easily melted;

6. When making the nozzle, the holes should be even and parallel, the inner wall should be smooth, and the welding place should be firm;

7. The number of fire holes depends on the size of the spray gun. The total area of fire holes should be the same as the area of the spray gun mouth.

CHAENG specializes in the production of rotary kiln, ball mill, vertical roller mill and other mining machinery and equipment accessories, welcome to contact us for quotation!