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Diganosis of pulley belt system faults using vibrations analysis
- 1. DIGANOSIS OF PULLEY-BELT SYSTEM FAULTS USING VIBRATIONS ANALYSIS BY : MSC. KHALID MOHSIN ALI SUPERVISION BY: Dr. ALI RAAD HASSAN UNIVERSITY OF TECHNOLOGY MECHANICAL ENGINEERING DEPARTMENT
- 2. Initial tension measurement Laser pulley alignment LaptopSteel structure bord of DC motor speed drive & Arduino mega DC motor Reflective tape of tachometers
- 3. Balancing pulleys Step 1 Pulley mounted with its shaft is go ahead to roll on two smooth and hard parallel horizontal shafts or knife- edges as shown in figure . The pulley rolls such that heavy spot rolls to the bottom due to gravity force. Some amount of material is removed at the high mass portion by drilling. The amount of unbalance of mass is unknown, but its location is known. By trial and error, material is slightly removed until no portions of excess mass on the pulley favors the bottom. The balanced pulley could be rolled into any position and released, it would remain stationary there
- 4. Step 2 This stage is more accurate than the previous one. Summarized by taking read of sensor 1 which mounted on one of drive shaft without pulley or any faults (healthy condition), at 1500 rpm, then assembled the unbalance pulley which want to balance it, and also taking reads at 1500 rpm the different between the two reads gives Indicate how much unbalance fault. unbalance condition gives at horizontal direction (x-direction of sensor) sinusoidal waveform (time domain spectrum) and gives peek at 1X (25Hz) in FFT spectrum, the height of this peek directly proportional with the amount of unbalance mass as described in the centrifugal laws. To reduce this height the excess mass must be equalized. For this purpose will use small pieces of magnets as shown . By adding these small masses on different positions until the signals of waveform and FFT spectrum becomes like at healthy condition. After reaching the balance state, each opposite points of magnets positions will punch and drill in equal mass. The result of this process shown.
- 5. Healthy condition (A) time domain waveform,(B) FFT spectrum. A B
- 6. Pulley before balancing at 1500 rpm, (A) time domain waveform, (B) FFT spectrum. A B 25 Hz
- 7. Pulley after balancing at 1500 rpm, (A) time domain waveform, (B) FFT spectrum. A B
- 9. DYNAMIC RESPONSE c a s e Case description rpm Drive and driven pulleys Diameters C cm Radius ratio 1 Rpm change 500 1000 1500 2000 10x10 37 1:1 2 Equal diameter of pulleys change 1500 10x10 15x15 20x20 25x25 37 1:1 3 Reduce ratio change 1500 10x10 10x15 10x20 10x25 37 1:1 1:1.5 1:2 1:2.5 4 Center distance change 1500 10x10 37 47 57 67 1:1
- 10. RPM CHANGE / V-BELT / C37 cm / AT RADIAL DIRECTION (HORIZONTAL) / INITIAL TENSION 30N 500 rpm 1000 rpm 1500 rpm 2000 rpm
- 12. C=37 Cm Equal pulleys diameters change. X-direction
- 13. Center distance change 37 cm 47 cm 57 cm 67 cm
- 14. faults V-belt resonance Stroboscope camera mobile application
- 15. Belt damage 𝑏𝑒𝑙𝑡 𝑟𝑎𝑡𝑒 = 𝜋 𝑋 1000 𝑋 0.25 60 𝑋 1.785 = 7.3 𝐻𝑧
- 16. THANK YOU FOR ATTENTION