Pulley shaft fracture
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It’s called a pulley shaft; more precisely, it’s the motor shaft. The device in question is a 1250 centrifuge, and it involves the pulley of the main motor. It had been in use for only two months when, at around 5 p.m. yesterday, it suddenly broke without any prior signs. Photo 1 is a photo of the motor side, Photo 2 is a photo of the pulley side, and Photo 3 is the \"front view\" of the pulley. The centrifuge is installed on a 12-meter steel structural frame; its supports are also made of steel, with the centrifuge being placed directly on these supports via four damping oil shock absorbers. I would appreciate it if experts could analyze what caused the fracture.
The centrifuge experiences some vibration during operation, but it’s not severe; generally, it’s between 9 and 12. In very rare cases, it reaches around 30, but such levels last for only a short time before the machine stops automatically or slows down.
As can be seen from Figure 2, some parts of the cross-section are rusted; there were likely cracks present beforehand, and as these cracks expanded the material lost sufficient strength and broke
The crack extends; when it can no longer bear the stress, it breaks
The centrifuge is placed directly on the supports via four damping oil shock absorbers. Here is a photo of the entire centrifuge and motor assembly
Personal analysis of the cause of the fracture: ① From the photos, it appears to be a gradual fracture; manufacturing defects in the shaft cannot be ruled out； ②What unit are the vibration values you described in? Use this to determine whether the vibration is above the limit ； ③After the accident, check whether the bearing seized; this can be used to determine if the shaft broke due to bearing seizure
The vibration value is in mm/s, and the motor rotates normally after the incident
The shaft likely has existing damage, possibly caused during processing; the cracks keep expanding, and coupled with periodic stress and fatigue damage, it eventually breaks
Install as shown in the figure below; the image depicts the construction process, with the I-beams of the secondary supports being connected to form a square shape
It is preliminarily judged that there are defects resulting from previous damage; since the equipment was manufactured and then stored for some time without being installed, this has led to some disputes