The eccentric shaft of the vibrating screen is driven by the motor for circular motion, and the counterweight block produces centrifugal force on the wheel shaft. Under the action of long-term alternating stress and strong stress concentration, the crack expands gradually from micro to macro. When the crack gradually expands to a certain limit, it suddenly expands rapidly, which seriously weakens the section of the member, and fracture occurs along the seriously weakened section. Below I will analyze the reasons for the eccentric shaft fracture of the vibrating screen and preventive measures.
A, vibrating screen eccentric shaft fracture reason
1. Long-term load shock
The vibrating screen shaft often bears the impact of eccentric and inertial load for a long time, resulting in the internal fatigue damage of the vibrating screen shaft. The bearing shaft diameter belongs to the stress concentration position. Because the vibrating screen shaft is an eccentric shaft, so in its original processing process, located in the offset connection part of the two axes, will occupy the diameter and step, and the resulting phenomenon of stress concentration.
2, triangle belt tension is too large
Vibrating screen eccentric shaft fracture is due to triangle belt tension is too large, resulting in long-term eccentric shaft under the action of alternating stress fatigue damage and fracture. According to the field situation, the vibrating screen is often started in the case of material, so the starting torque is larger, because the material is started so the belt tension increases, so the eccentric shaft force is relatively increased, in the long-term action will occur fatigue failure.
3. Unreasonable configuration of production process system
In the process of using the vibrating screen, it was found that one side of the bearing is more seriously worn than the other side of the bearing, the continuous operation time of the broken section is longer, the ventilation condition of the work site is poor, resulting in poor heat dissipation of the bearing and the journal. Coupled with the side bearing wear is serious, leading to the rotation of the bearing roller and the increase of the axial clearance, leading to the irregular movement of the roller, if the rotational torque caused by the bearing roller stuck, will also cause the shaker shaft fracture.
4, eccentric shaft processing is not reasonable
(1) Due to the loose matching position of the journal and the bearing, in the process of shaft repair, the common electrode is used to surfacing the journal at the matching position of the bearing inner hole, and then the lathe is used to turn, leading to the stress concentration at the journal. Does not eliminate the stress of the shaker shaft after rotation.
Eccentric shaft (2) in the repair process, as a result of the limitation of processing unit process and processing ability, the eccentric shaft caused by the deviation between the two line more than the original design parameter (greater than or less than), belongs to the machining defects, such as the deflection Angle is too large, lead to vibrating screen in the process of operation, destroyed the original vibration frequency and amplitude, and result in vibrating screen shaft fatigue, then will appear broken shaft.
(3) Due to maintenance or other reasons, vibration frequency changes when vibrating screen work, and vibrating screen itself resonance phenomenon, because the vibrating screen is a continuous operation of equipment, long-term use, vibrating screen shaft shaft phenomenon.
(4) Vibrating screen in the use of the process, bearing improper selection will also cause the “holding shaft” phenomenon.