There are two kinds of the ball mill gear  broken： One is fatigue fracture ; Another kind is overload fracture . The main cause of fatigue fracture are: The transmission system of transmission load is too large ; The gear‘s radius is too small ; gear root surface roughness is too large   ; roll and gnashing of teeth when the roots are strained ; defective materials , heat treatment produces tiny cracks and other harmful residual stress .

 

 When the ball mill gear root in alternating stress than the fatigue limit of material, the gear root fillet area will produce fatigue crack, crack expanding again, eventually led to the gear bending fatigue fracture. And overload fracture is usually due to the impact of short-term serious overload, make the stress of the tooth to bear more than the limit stress caused by. Load serious concentrated, dynamic load is too large and has a larger hard foreign body into the tooth mesh, all can cause overload fracture.

 

  Ball mill gear fatigue fracture is in long-term under the action of alternating stress gradually . Due to the small number of teeth of the pinion , a relatively large number of cycles of stress , fatigue fracture is also possible. But mill drive system dynamic load generally not great , and indeed before each replacement gear involute new parameters , gear accuracy, surface quality are measured and tested , the test results are in line with the technical requirements of the drawings , a single when replacing the pinion mill several broken the elapsed time from the point of view, should be the common effect of fatigue and overload .

 

    However, when several broken, no serious accidents overload occurs, mill work, there is not much impact loads , without excessive transmission of dynamic loads , and every time a fault occurs, rounds round meshing place, there is no hard foreign body in the meantime . Obviously, the main reason for broken teeth should be focused on serious load on the gear teeth . About After this point , the field staff of two rounds with red lead powder coloring meshing of the inspection confirmed. On-site inspection found the tooth surface contact area , although up to 90 %, but close to the end of the colored cylinder is significantly heavier , and near one end of the coupling is significantly lighter , the former accounted for only 50% of the tooth surface . So , think of a few broken teeth are near the end of the barrel , because the work load is concentrated , leading to a small gear repeatedly broken.